HESI Physics Questions with Answers
and Explanations
1. When a junked car is compacted, which statement is true?
A. Its mass increases.
B. Its mass decreases.
C. Its density increases.
D. Its density decreases.
Explanation: Since density = mass/volume, it should be obvious that the decrease in volume as a
car is crushed should lead to an increase in density. Nothing happens to change the mass of the
car.
2. A car travels 3 miles north, 6 miles south, 2 miles east, 2 miles west, and then 3 miles
north. Which of the following is true?
A. The displacement of the car is 16 miles, and the distance traveled is 0 miles.
B. The displacement of the car is 16 miles, and the distance traveled is 16 miles.
C. The displacement of the car is 0 miles, and the distance traveled is 0 miles.
D. The displacement of the car is 0 miles, and the distance traveled is 16 miles.
Expalanation: If a car travels 3 miles north, 6 miles south, 2 miles east, 2 miles west, and then 3
miles north, it has traveled a total distance of 16 miles. However, because of the directions it has
traveled, it has ended up in the place where it started, giving it a displacement of 0.
3. Why doesn’t a raindrop accelerate as it approaches the ground?
A. Gravity pulls it down at a constant rate.
B. Air resistance counteracts the gravitational force.
C. Its mass decreases, decreasing its speed.
D. Objects in motion decelerate over distance.
Explanation: Gravity in fact causes acceleration, making choice A incorrect— unless air
resistance counteracts that acceleration, which it may easily do for an object as small and
, lightweight as a raindrop. Raindrops may lose mass (choice C), but that would not decrease their
acceleration. Choice D violates Newton’s first law.
4. An object moves 100 m in 10 s. What is the velocity of the object over this time?
A. 10 m/s
B. 90 m/s
C. 110 m/s
D. 1,000 m/s
Explanation: Velocity is the change in distance over time. 100 m/10 s is the same as 10 m/s.
5. Which of these objects has the greatest momentum?
A. A 1,250-kg car moving at 5 m/s
B. An 80-kg person running at 4 m/s
C. A 10-kg piece of meteorite moving at 600 m/s
D. A 0.5-kg rock moving at 40 m/s
Explanation: Momentum is calculated by multiplying mass by velocity, p = mv. Although the
meteorite seems intimidating, it is the car that has the greatest momentum, at 6,250 kg⋅m/s.
6. Sublimation is the change in matter from solid to gas or gas to solid without passing
through a liquid phase. Outside of the laboratory, which solid provides the best example of this?
A. Iron
B. Silver
C. Salt crystal
D. Dry ice
Explanation: Dry ice is frozen carbon dioxide. As it breaks down, it transforms directly into gas
without passing through a liquid phase. Sublimation of metals is possible, but not “outside of the
laboratory.”
and Explanations
1. When a junked car is compacted, which statement is true?
A. Its mass increases.
B. Its mass decreases.
C. Its density increases.
D. Its density decreases.
Explanation: Since density = mass/volume, it should be obvious that the decrease in volume as a
car is crushed should lead to an increase in density. Nothing happens to change the mass of the
car.
2. A car travels 3 miles north, 6 miles south, 2 miles east, 2 miles west, and then 3 miles
north. Which of the following is true?
A. The displacement of the car is 16 miles, and the distance traveled is 0 miles.
B. The displacement of the car is 16 miles, and the distance traveled is 16 miles.
C. The displacement of the car is 0 miles, and the distance traveled is 0 miles.
D. The displacement of the car is 0 miles, and the distance traveled is 16 miles.
Expalanation: If a car travels 3 miles north, 6 miles south, 2 miles east, 2 miles west, and then 3
miles north, it has traveled a total distance of 16 miles. However, because of the directions it has
traveled, it has ended up in the place where it started, giving it a displacement of 0.
3. Why doesn’t a raindrop accelerate as it approaches the ground?
A. Gravity pulls it down at a constant rate.
B. Air resistance counteracts the gravitational force.
C. Its mass decreases, decreasing its speed.
D. Objects in motion decelerate over distance.
Explanation: Gravity in fact causes acceleration, making choice A incorrect— unless air
resistance counteracts that acceleration, which it may easily do for an object as small and
, lightweight as a raindrop. Raindrops may lose mass (choice C), but that would not decrease their
acceleration. Choice D violates Newton’s first law.
4. An object moves 100 m in 10 s. What is the velocity of the object over this time?
A. 10 m/s
B. 90 m/s
C. 110 m/s
D. 1,000 m/s
Explanation: Velocity is the change in distance over time. 100 m/10 s is the same as 10 m/s.
5. Which of these objects has the greatest momentum?
A. A 1,250-kg car moving at 5 m/s
B. An 80-kg person running at 4 m/s
C. A 10-kg piece of meteorite moving at 600 m/s
D. A 0.5-kg rock moving at 40 m/s
Explanation: Momentum is calculated by multiplying mass by velocity, p = mv. Although the
meteorite seems intimidating, it is the car that has the greatest momentum, at 6,250 kg⋅m/s.
6. Sublimation is the change in matter from solid to gas or gas to solid without passing
through a liquid phase. Outside of the laboratory, which solid provides the best example of this?
A. Iron
B. Silver
C. Salt crystal
D. Dry ice
Explanation: Dry ice is frozen carbon dioxide. As it breaks down, it transforms directly into gas
without passing through a liquid phase. Sublimation of metals is possible, but not “outside of the
laboratory.”
