Practice Test 7 - Middle School Physical Science

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

Start practice test

1. A student uses iron filings on paper over a bar magnet. The student concludes: "This experiment shows the entire 3D magnetic field around the magnet." Which statement best evaluates that conclusion?
2. A student tests a cold pack with these criteria: Criterion 1 (quick cooling): Reach $0\text{–}5^\circ\text{C}$ within 2 minutes. Criterion 2 (stays cold): Stay below $10^\circ\text{C}$ for at least 30 minutes. Test procedure: Activate the cold pack, then record temperature using a thermometer at the times shown. Data (time, temperature): 0 min: $22^\circ\text{C}$, 1 min: $7^\circ\text{C}$, 2 min: $4^\circ\text{C}$, 10 min: $3^\circ\text{C}$, 20 min: $6^\circ\text{C}$, 30 min: $9^\circ\text{C}$, 35 min: $11^\circ\text{C}$. Which statement best evaluates the cold pack against the criteria?
3. A cooler failed because too much ice melted: 1000 g to 720 g in 6 hours (280 g melted; must be $\le 200$ g). The cooler has 2 cm foam walls and is used outside on a sunny day; its exterior is dark blue. Which modification best reduces heat gain by radiation from the Sun?
4. Two magnets are tested with the same type of paper clips at the same distance (the clip starts 1 cm from the magnet). Condition A: Weak ceramic magnet → picks up 3 paper clips. Condition B: Strong neodymium magnet → picks up 14 paper clips. What is the best evidence-based conclusion about magnetic force?
5. A student plans to test which material insulates best (foam, plastic, fiberglass) by tracking how fast hot water cools. Which safety step is most appropriate to include?
6. Two students describe a substance: Student 1: "It is made of identical groups of atoms, and each group stays together as a unit. There is space between the groups." Student 2: "It is made of atoms/ions bonded in a repeating pattern that continues throughout the solid, so there are no separate units." Which student is describing a molecular substance, and which is describing an extended crystal structure?
7. Which communication method would still work between two astronauts floating in space with no air between them?
8. A student says, "Jupiter pulls on a 1 kg object with 25 N, but the 1 kg object pulls on Jupiter with a much smaller force." Which statement is correct?​
9. A heavy book rests on a table without moving. Which forces form an action-reaction pair according to Newton's Third Law?
10. A student investigates: Which insulation material keeps water hot longest? They plan to measure the temperature after 60 minutes. Which set lists controlled variables that should be kept the same in every trial?
11. A computer orbital simulation uses only gravity between a star and a planet. When the planet starts with a sideways (tangential) speed, the model predicts a repeating elliptical path around the star instead of a straight-line path. Which claim is best supported by these simulation results?
12. On Earth, $g \approx 10\ \text{N/kg}$. If a 3 kg object has a weight of about 30 N, what would be the weight of a 6 kg object on Earth?
13. A teacher demonstrates two temperature readings: an analog thermometer where the liquid level can be between marks, and a digital thermometer that rounds to the nearest 0.1°C. What digital limitation does this demonstrate?
14. A student pushes a book to the right across a table with a 15 N force. Friction on the book is 10 N to the left. What is the net force on the book, and what will happen to its motion?
15. Two air-track gliders collide with spring bumpers. Glider A has mass $1\,\text{kg}$ and Glider B has mass $3\,\text{kg}$. During the brief collision, both gliders' velocities change, but Glider A's speed changes much more. Which statement best explains this?
16. Look at the particle models: Substance A is oxygen gas ($\mathrm{O_2}$) and Substance B is water ($\mathrm{H_2O}$). Which substance is a pure element (made of only one type of atom)?
17. A student investigates a magnetic field by placing a sheet of paper over a bar magnet and sprinkling iron filings on top. The student gently taps the paper and observes that the filings form curved lines from one end of the magnet to the other. The filings are most crowded near the ends of the magnet and more spread out farther away. What does this investigation demonstrate about the magnetic field, and what is a key limitation of this method?
18. A bathroom window should let daylight into the room but prevent people outside from seeing clear images inside. Which material choice best fits this purpose?
19. A 1 kg book is placed on three different levels in a classroom. The floor is the reference level where $h=0$ m. Shelf heights above the floor are 1 m (low shelf) and 2 m (high shelf). Using $g \approx 10\ \text{m/s}^2$, what is the book's gravitational potential energy on the 2 m shelf?
20. A vehicle bumper must prevent vehicle damage in a 5 mph collision and should be affordable. Test results: Design A prevents damage but is expensive; Design B is cheap but allows damage; Design C prevents damage and has medium cost. If preventing damage is a must-have requirement, which design should be chosen?

Practice tests