Predict Energy Changes from Speed - 4th Grade Science

1. Fatima rolls a ball that is moving medium-fast, so it has some kinetic energy. The ball will hit a rug and slow down until it stops. When the ball stops moving, its kinetic energy will ___.
   Answer: will become zero This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Fatima's ball is moving medium-fast and will slow down until it stops completely. The ball's speed will become zero, so we can predict its kinetic energy will become zero. For example, when the ball comes to rest on the rug, it has no motion and therefore no kinetic energy. Choice A is correct because it accurately predicts that kinetic energy will become zero when speed becomes zero. This prediction follows the speed-energy rule and shows the student understands that kinetic energy only exists during motion. Choice D is incorrect because it suggests energy will still be high when stopped. This is a common error where students think a previously fast object retains its energy even after stopping, not understanding that kinetic energy requires motion. The key understanding is that kinetic energy completely disappears when objects stop moving. To help students make predictions: Create 'if-then' rules together ('If it stops moving, then kinetic energy is zero'). Practice with examples across different contexts (ball stopping, toy car coming to rest, swing at lowest point) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects always have zero kinetic energy, no matter how fast they were moving before.
2. Marcus starts a sled moving slowly at the top of a hill, and it will speed up going down. How will the sled's kinetic energy change as its speed increases?
   Answer: It will increase. This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Marcus starts a sled moving slowly at the top of a hill and it speeds up going down. The sled's speed will increase, so we can predict its kinetic energy will increase. For example, when the sled speeds up going down the hill, it will have more kinetic energy at the bottom. Choice A is correct because it accurately predicts that kinetic energy will increase when speed increases. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice B is incorrect because it predicts the kinetic energy will decrease. This is a common error where students reverse the relationship. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed increases, then energy increases'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
3. Jamal is riding his bike fast and then will brake to a stop sign. When the bike stops moving, what will happen to its kinetic energy?
   Answer: It will become zero. This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Jamal is riding his bike fast but brakes to a complete stop at the stop sign. The bike's speed will become zero, so we can predict its kinetic energy will become zero. For example, when the bike stops moving, it will have no kinetic energy left. Choice B is correct because it accurately predicts that kinetic energy will become zero when speed stops. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice A is incorrect because it predicts the kinetic energy will stay the same. This is a common error where students think energy stays when the object stops. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed becomes zero, then energy becomes zero'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
4. Chen's wind-up toy car starts slow, then will speed up; how will kinetic energy change?
   Answer: It will increase. This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Chen's wind-up toy car starts slow and then speeds up. The car's speed will increase, so we can predict its kinetic energy will increase. For example, when the car speeds up after winding, it will have more kinetic energy as it moves faster. Choice B is correct because it accurately predicts that kinetic energy will increase when speed increases. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice A is incorrect because it predicts kinetic energy will decrease. This is a common error where students reverse the relationship, thinking faster means less energy. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed increases, then energy increases'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
5. Maya is at the top of a playground slide, starting to move slowly. She will slide down and speed up as she goes. When Maya moves faster at the bottom, her kinetic energy will ___.
   Answer: will increase This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Maya starts moving slowly at the top of a slide and will speed up as she slides down. Maya's speed will increase, so we can predict her kinetic energy will increase. For example, when Maya reaches the bottom moving fast, she will have much more kinetic energy than at the slow-moving top. Choice B is correct because it accurately predicts that kinetic energy will increase when speed increases. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice A is incorrect because it predicts energy decreases. This is a common error where students might think going down means less energy, not recognizing that faster speed always means more kinetic energy regardless of direction. The key understanding is that kinetic energy depends on speed, not position or direction. To help students make predictions: Create 'if-then' rules together ('If you go faster, then you have more energy'). Practice with examples across different contexts (sliding down, rolling downhill, falling objects) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that speed is what matters for kinetic energy, not whether you're going up or down.
6. Emma is at the top of a slide moving very slowly, but she will speed up going down. When she speeds up, what will happen to her kinetic energy?
   Answer: It will increase. This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Emma is at the top of a slide moving slowly but speeds up as she goes down. Her speed will increase, so we can predict her kinetic energy will increase. For example, when she speeds up going down the slide, she will have more kinetic energy at the bottom. Choice C is correct because it accurately predicts that kinetic energy will increase when speed increases. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice A is incorrect because it predicts the kinetic energy will decrease. This is a common error where students reverse the relationship. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed increases, then energy increases'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
7. Maya winds up a toy car that starts slow and then will speed up across the floor. If the car's speed increases, its kinetic energy will ___.
   Answer: increase This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Maya winds up a toy car that starts slow and then speeds up across the floor. The car's speed will increase, so we can predict its kinetic energy will increase. For example, as the toy car speeds up, it will have more kinetic energy than when it started slow. Choice D is correct because it accurately predicts that kinetic energy will increase when speed increases. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice B is incorrect because it predicts the kinetic energy will decrease. This is a common error where students reverse the relationship. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed increases, then energy increases'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
8. Keisha rides her bike at medium speed, then will slow down near a stop sign; kinetic energy will ___.
   Answer: It will decrease. This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Keisha rides her bike at medium speed and then slows down near a stop sign. The bike's speed will decrease, so we can predict its kinetic energy will decrease. For example, as she slows down, the bike will have less kinetic energy. Choice A is correct because it accurately predicts that kinetic energy will decrease when speed decreases. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice D is incorrect because it predicts kinetic energy will become zero right away. This is a common error where students think slowing means instant stop. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed increases, then energy increases'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
9. Carlos is riding his bike quickly, so his kinetic energy is high. He will coast up to a stop sign and slow down a lot. As Carlos slows down, his kinetic energy will ___.
   Answer: will decrease This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Carlos is riding quickly with high kinetic energy and will slow down for a stop sign. The bike's speed will decrease, so we can predict its kinetic energy will decrease. For example, as Carlos coasts and slows from fast to slow, he loses kinetic energy. Choice C is correct because it accurately predicts that kinetic energy will decrease when speed decreases. This prediction follows the speed-energy rule and shows the student understands that less speed always means less energy. Choice D is incorrect because it predicts the energy turns into potential energy. This is a common error where students think energy must transform rather than simply decrease - kinetic energy can just become less without turning into something else. The key understanding is that kinetic energy decreases whenever objects slow down. To help students make predictions: Create 'if-then' rules together ('If you slow down, then you have less energy'). Practice with examples across different contexts (coasting bike, slowing car, person walking slower) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that slowing down always means losing kinetic energy.
10. Sofia pushes a wagon that is sitting still with zero speed. The wagon will start moving and get faster across the sidewalk. When the wagon starts moving faster, its kinetic energy will ___.
    Answer: will increase This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Sofia pushes a wagon that starts at rest (zero speed) and will get faster. The wagon's speed will increase from zero, so we can predict its kinetic energy will increase from zero. For example, as the wagon rolls faster across the sidewalk, it gains more and more kinetic energy. Choice A is correct because it accurately predicts that kinetic energy will increase when speed increases from zero. This prediction follows the speed-energy rule and shows the student understands that kinetic energy appears when motion begins. Choice D is incorrect because it predicts the energy turns into potential energy. This is a common error where students confuse different types of energy or think one must transform into another. The key understanding is that kinetic energy is created when objects start moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If something starts moving, then kinetic energy appears'). Practice with examples across different contexts (pushing a box, kicking a ball, starting a toy car) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts.
11. A ball is rolling fast, but friction will slow it down; what will kinetic energy do?
    Answer: It will decrease. This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, a ball is rolling fast but friction will slow it down. The ball's speed will decrease, so we can predict its kinetic energy will decrease. For example, as the ball slows due to friction, it will have less kinetic energy over time. Choice B is correct because it accurately predicts that kinetic energy will decrease when speed decreases. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice D is incorrect because it predicts kinetic energy will become zero right away. This is a common error where students think slowing means instant stop. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed increases, then energy increases'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
12. Jamal is riding his bike fast and has a lot of kinetic energy. He will squeeze the brakes until the bike stops. When the bike stops moving, its kinetic energy will ___.
    Answer: will become zero This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Jamal's bike is moving fast and will come to a complete stop. The bike's speed will become zero, so we can predict its kinetic energy will become zero. For example, when the bike stops at a red light, it has no motion and therefore no kinetic energy. Choice B is correct because it accurately predicts that kinetic energy will become zero when speed stops. This prediction follows the speed-energy rule and shows the student understands that kinetic energy only exists when there is motion. Choice D is incorrect because it predicts the energy turns into potential energy. This is a common error where students think energy must go somewhere rather than understanding that kinetic energy simply disappears when motion stops. The key understanding is that kinetic energy only exists when something is moving, and zero speed always means zero kinetic energy. To help students make predictions: Create 'if-then' rules together ('If speed becomes zero, then kinetic energy becomes zero'). Practice with examples across different contexts (car stopping, ball coming to rest, person standing still) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
13. Carlos rolls a ball fast, but it will keep slowing down until it stops. When the ball stops moving, its kinetic energy will ___.
    Answer: become zero This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Carlos rolls a ball fast but it slows down until it stops. The ball's speed will become zero, so we can predict its kinetic energy will become zero. For example, when the ball stops moving completely, it will have no kinetic energy. Choice C is correct because it accurately predicts that kinetic energy will become zero when speed stops. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice A is incorrect because it predicts the kinetic energy will increase. This is a common error where students think energy stays when the object stops. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed becomes zero, then energy becomes zero'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
14. Yuki rides her bike fast, but she will squeeze the brakes and slow down. As the bike slows down, predict what happens to its kinetic energy.
    Answer: It will decrease. This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Yuki rides her bike fast but squeezes the brakes to slow down. The bike's speed will decrease, so we can predict its kinetic energy will decrease. For example, as the bike slows down with brakes, it will have less kinetic energy than when it was going fast. Choice C is correct because it accurately predicts that kinetic energy will decrease when speed decreases. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice A is incorrect because it predicts the kinetic energy will increase. This is a common error where students reverse the relationship. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed decreases, then energy decreases'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
15. A sled starts slow at the top, then will speed up going downhill; kinetic energy will ___.
    Answer: It will increase. This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, a sled starts slow at the top and then speeds up going downhill. The sled's speed will increase, so we can predict its kinetic energy will increase. For example, when the sled speeds up going down the hill, it will have more kinetic energy at the bottom. Choice B is correct because it accurately predicts that kinetic energy will increase when speed increases. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice D is incorrect because it predicts kinetic energy will be zero because it is outside. This is a common error where students think environment affects the rule. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed increases, then energy increases'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
16. Yuki is pushing a wagon that is moving slowly with low kinetic energy. She will push harder and the wagon will speed up. When the wagon speeds up, its kinetic energy will ___.
    Answer: will increase This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Yuki's wagon is moving slowly with low kinetic energy and will speed up when pushed harder. The wagon's speed will increase, so we can predict its kinetic energy will increase. For example, when Yuki pushes harder and the wagon goes faster, it gains more kinetic energy. Choice C is correct because it accurately predicts that kinetic energy will increase when speed increases. This prediction follows the speed-energy rule and shows the student understands that more speed always means more energy. Choice A is incorrect because it predicts energy decreases. This is a common error where students might think pushing takes energy away rather than adding it, not recognizing that faster motion always means more kinetic energy. The key understanding is that kinetic energy increases whenever speed increases, regardless of the starting amount. To help students make predictions: Create 'if-then' rules together ('If you make something go faster, then it has more energy'). Practice with examples across different contexts (pushing harder, pedaling faster, throwing harder) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that increasing speed always increases kinetic energy, no matter how the speed increase happens.
17. Fatima rolls a ball, but it will slow down until it stops; what will kinetic energy do?
    Answer: It will become zero. This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Fatima rolls a ball but it will slow down until it stops. The ball's speed will decrease to zero, so we can predict its kinetic energy will become zero. For example, when the ball finally stops, it will have no kinetic energy. Choice C is correct because it accurately predicts that kinetic energy will become zero when speed stops. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice A is incorrect because it predicts kinetic energy will stay the same. This is a common error where students think energy stays when object stops. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed increases, then energy increases'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
18. Emma starts down a slide slowly, then will move faster at the bottom; kinetic energy will ___.
    Answer: It will increase. This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Emma starts down a slide slowly and then moves faster at the bottom. Emma's speed will increase, so we can predict her kinetic energy will increase. For example, when she speeds up going down the slide, she will have more kinetic energy at the bottom. Choice A is correct because it accurately predicts that kinetic energy will increase when speed increases. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice D is incorrect because it predicts kinetic energy will be zero because she is low. This is a common error where students confuse height with speed. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed increases, then energy increases'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
19. Marcus rides his bike fast, then will brake to a stop; what will kinetic energy do?
    Answer: It will become zero. This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Marcus rides his bike fast and then brakes to a stop. The bike's speed will decrease to zero, so we can predict its kinetic energy will become zero. For example, when the bike comes to a complete stop, it will have no kinetic energy left. Choice C is correct because it accurately predicts that kinetic energy will become zero when speed stops. This prediction follows the speed-energy rule and shows the student understands the direct relationship between these two variables. Choice D is incorrect because it predicts kinetic energy will only decrease without reaching zero. This is a common error where students think energy stays when the object stops. The key understanding is that kinetic energy only exists when something is moving, and more speed always means more energy. To help students make predictions: Create 'if-then' rules together ('If speed increases, then energy increases'). Practice with examples across different contexts (ball rolling, person running, car driving) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that stopped objects have zero kinetic energy - energy appears when motion starts, disappears when motion stops.
20. Diego has a wind-up toy car that is moving slowly at first. After he releases it, the toy car will speed up across the floor. If the car's speed increases, its kinetic energy will ___.
    Answer: will increase This question tests 4th grade ability to predict how an object's kinetic energy changes when its speed changes (NGSS 4-PS3-1). Students must understand the direct relationship between speed and kinetic energy to make accurate predictions. The rule for predictions: when speed increases, kinetic energy increases; when speed decreases, kinetic energy decreases; when an object stops (speed becomes zero), kinetic energy becomes zero. This relationship is always true - speed and kinetic energy always change in the same direction. In this scenario, Diego's toy car is moving slowly at first and will speed up after release. The car's speed will increase, so we can predict its kinetic energy will increase. For example, as the wind-up mechanism makes the car go faster, it gains more kinetic energy. Choice C is correct because it accurately predicts that kinetic energy will increase when speed increases. This prediction follows the speed-energy rule and shows the student understands that more speed always means more energy. Choice A is incorrect because it predicts energy stays the same. This is a common error where students think the wind-up toy has a fixed amount of energy that doesn't change, not understanding that kinetic energy changes with speed. The key understanding is that kinetic energy increases whenever speed increases, regardless of what causes the speed change. To help students make predictions: Create 'if-then' rules together ('If speed goes up, then energy goes up'). Practice with examples across different contexts (wind-up toys, pushed objects, rolling balls) to show pattern holds everywhere. Use before/after comparisons: have students predict, then observe to confirm. Emphasize that the source of motion doesn't matter - more speed always means more kinetic energy.

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