Practice Test 5 - Middle School Physical Science

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

A 3 kg backpack is on a shelf 2 m above the floor. Using $g\approx 10\,\text{m/s}^2$ , what is its gravitational potential energy relative to the floor?
A student says, "If two objects collide and one stops while the other keeps moving, the moving one must have exerted a larger force." Which response is best?
A $5\,\text{kg}$ toolbox is lifted straight up from $h=0\,\text{m}$ to $h=2\,\text{m}$ , then lifted again to $h=5\,\text{m}$ . Take $g=10\,\text{m/s}^2$ . How much gravitational potential energy is gained from $h=2\,\text{m}$ to $h=5\,\text{m}$ ?
In the particle model of carbon dioxide (CO₂), the black C atom is in the center and is connected to two red O atoms. How many oxygen (O) atoms are in one CO₂ molecule?
A student tests insulation thickness using 1 cm, 2 cm, 3 cm, and 4 cm of foam. They accidentally use 250 mL of water in one container and 400 mL in another. What is the main problem with changing water volume during this investigation?
A sample of oxygen gas is made of many separate $\mathrm{O_2}$ units moving around. A sample of table salt ( $\mathrm{NaCl}$ ) is made of $\mathrm{Na^+}$ and $\mathrm{Cl^-}$ in a repeating pattern throughout the solid. Which statement correctly compares their structures?
In polymerization, thousands of small molecules (monomers) join to form a polymer (plastic). Which description correctly explains what happens to the molecules during polymerization?
A comparative test is done on three insulated container designs. Criterion: keep hot water above $60\,^{\circ}\mathrm{C}$ for 4 hours. Test procedure: Each container starts with $80\,^{\circ}\mathrm{C}$ water. Temperatures are measured at hour 4. Results: - Design A: $58\,^{\circ}\mathrm{C}$ at 4 hours - Design B: $61\,^{\circ}\mathrm{C}$ at 4 hours - Design C: $60\,^{\circ}\mathrm{C}$ at 4 hours Which designs meet the criterion?
Which list includes only forces that can act at a distance (without objects touching)?
Steam (water vapor, a gas) above a pot is cooled from $100^\circ\text{C}$ to $50^\circ\text{C}$ as it touches a cooler lid. Thermal energy is removed from the steam. What is the most likely result on the lid?
Seismic waves from an earthquake travel through Earth. P-waves can travel through rock and liquid, but S-waves travel through rock and do not travel through liquids. What does this show about wave behavior in different media?
A class records ocean tide heights for a week and compares them to the Moon's position. They observe higher tides occur when the Moon is overhead and again about 12 hours later when the Moon is on the opposite side of Earth. Which claim is best supported by these observations?
A student rubs a balloon on their hair and then holds the balloon about 2 cm above tiny pieces of paper. The balloon does not touch the paper, but several pieces leap up to the balloon. Which type of force is acting at a distance in this situation?
A $2\,\text{kg}$ ball is held at rest at three different heights above the ground: $h=0\,\text{m}$ , $h=2\,\text{m}$ , and $h=4\,\text{m}$ . Ignore air resistance and take $g\approx 10\,\text{N/kg}$ . Which statement correctly connects force direction, work, and gravitational potential energy (PE)?
Water waves move across a lake and reach a shallow area near the shore. What change is most likely observed as the waves enter the shallow water? Wave type: water surface waves Condition A: deep water Condition B: shallow water near shore
A student drops a ball and measures its speed each second. The speed increases each second as it falls. Which statement best explains this change in speed near Earth's surface (ignore air resistance)?
A student cools a balloon filled with air from 25 degrees Celsius to 5 degrees Celsius. What change should the student expect in the average motion of the air particles inside the balloon?
A musician plays a melody on a flute. The sound waves travel through the air to a listener. Which change in the sound wave mainly tells the listener that the notes are getting higher in pitch?
A student claps in an empty hallway and hears an echo. Which wave behavior is mainly responsible for the echo when the sound hits a hard wall?
A student built an insulated cup using a foam cup with 0.5 cm-thick walls and a plastic lid that was not sealed tightly (no reflective coating). For the test, the student poured hot water at $70^\circ\text{C}$ into the cup, put the lid on, left it in a $25^\circ\text{C}$ room, and measured the water temperature each hour with a thermometer (± $1^\circ\text{C}$ ). Data: 0 hr: $70^\circ\text{C}$ , 1 hr: $58^\circ\text{C}$ , 2 hr: $48^\circ\text{C}$ , 3 hr: $40^\circ\text{C}$ . Criterion: maintain temperature $\ge 60^\circ\text{C}$ for 3 hours. Did the insulated cup meet the criterion (pass or fail)?

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