Practice Test 10 - Middle School Physical Science

20 questions. Answer them in any order, then submit to see your score and every explanation.

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1. A student brings a charged balloon near small bits of paper. The paper bits jump toward the balloon without touching it at first. Which statement best explains how this provides evidence for an electric field?
2. Two hot lunch container designs were tested for 4 hours. - Design A: basic foam insulation; temperature after 4 hours was 58°C; cost $12. - Design B: foam insulation + reflective interior lining; temperature after 4 hours was 64°C; cost $18. Criteria: temperature must be ≥60°C after 4 hours and cost must be less than $20. Which statement is the best evaluation?
3. A student stirs sugar into water and later evaporates the water, leaving white sugar crystals behind again. Before dissolving: sugar crystals are visible. After dissolving: solution is clear and sweet. After evaporation: crystals reappear. What is the best conclusion about the dissolving step?
4. A student investigates: How does starting temperature affect cooling rate? They keep the cup type and water volume the same, and they calculate cooling rate in °C/min. Which variable is the dependent variable?
5. Two identical carts (same mass) are on different tracks. Cart A is at height $h=8\,\text{m}$ and Cart B is at height $h=3\,\text{m}$, measured from the same reference level. Which comparison is correct for their gravitational potential energies?
6. A $0.20\,\text{kg}$ cue ball moving at $3.0\,\text{m/s}$ hits a stationary $0.20\,\text{kg}$ target ball. After the collision, the cue ball stops and the target ball moves at about $3.0\,\text{m/s}$. Which statement best describes the kinetic energy (KE) transfer?
7. Three water waves have amplitudes 1 cm, 2 cm, and 3 cm. Since $E \propto A^2$, which list correctly ranks the waves from least energy to most energy?
8. A student mixes vinegar and baking soda in a cup. The mixture fizzes, bubbles rapidly, and the cup feels cooler. Which evidence best supports that a chemical reaction occurred?
9. Hot lunch container design challenge: You need to design an insulated container that keeps 500 mL of soup hot from 7:00 AM until 12:00 PM (5 hours). The soup must stay at or above 60°C at lunchtime (safe eating temperature). The container must cost under $20, be no more than 15 cm tall so it fits in a backpack, be safe for students (the outside should not be hot enough to burn), and you may use only plastic, foam, and metal materials. Which option lists the criteria (performance goals) for this design?
10. A particle model shows particles close together but not in a repeating pattern. If this substance is poured into a different-shaped container, what will most likely happen?
11. A student mixes a spoonful of baking soda and vinegar in a cup. Before mixing: - Baking soda: white powder, no smell - Vinegar: clear liquid with a sharp smell After mixing: - The mixture fizzes and makes many bubbles - The cup feels slightly colder - A new gas seems to be produced (bubbling continues for a short time) Based on these observations, did a chemical reaction occur, and what is the best evidence?
12. A force-time graph is made for two carts during a collision. At every time shown, Cart A's sensor reads the same force magnitude as Cart B's sensor, but with opposite sign (one positive, one negative). What does this most directly indicate?
13. A playground is choosing a surface under a climbing structure to reduce injuries from falls. Which surface would best reduce the peak force on a child who lands on it, and why?​
14. A factory uses natural gas (mostly CH₄) and air to make ammonia (NH₃) for fertilizer. The process uses high temperature, high pressure, and a catalyst. Which statement best describes the chemical change that makes ammonia?
15. A student says, "If I graph kinetic energy (KE) vs speed for a constant mass, it should be a straight line because speed increases evenly." Which choice best corrects the student using the kinetic energy formula $\text{KE}=\tfrac{1}{2}mv^2$?
16. In a sealed jar (closed system), steel wool rusts. The student records the following. Mass data (g): - Before: jar + contents = 100 g - After: jar + contents = 100 g Which statement correctly connects conservation of atoms to conservation of mass in this reaction?
17. A student lines a music practice room with thick, soft, porous acoustic foam. The foam is designed to reduce echoes. What is the main wave behavior the foam causes for sound waves hitting it?
18. A student mixes two solutions in a sealed container. The mass of the sealed container and contents is 64.9 g before mixing and 64.9 g after mixing (±0.1 g). A solid forms (a precipitate), showing a chemical change occurred. Which statement best explains why the mass stayed the same?
19. A pendulum bob is pulled to the side and released. It swings back and forth. Which statement best explains why it starts moving back toward the center after being released?
20. A student held a charged rod near an electroscope and measured the angle the leaves separated (bigger angle = stronger electric effect). What does the data show about electric force and distance?

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