Title: Mid-Unit Assessment
Course: MNPCC Physics > Section: Energy

Use this quiz to see how your knowledge of the content is progressing.

Q: Which statement best describes what happens when brakes stop a car?
- The brakes transform the cars kinetic energy into thermal energy. (Correct.)
- The brakes destroy the kinetic energy of the car using friction. (Energy cannot be created or destroyed.)
- The brakes decrease the forward force on the car. (Decreasing a forward force would not cause the car to necessarily slow.)
A: The brakes transform the cars kinetic energy into thermal energy.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Two student jump with equal force.  Student A pushes on the floor while rising 0.1 m. Student B pushes on the floor while rising 0.2 m.  Who will leave the ground faster?
- Student B (Correct.)
- Student A. (Distance matters.)
- They leave the ground at the same speed. (Distance matters.)
A: Student B
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: The following diagram shows a the path of a roller coaster.  At what point does the pendulum have the highest gravitational potential energy?
- Position A and C are equivalent. (They are not equivalent.)
- Position A (Correct)
- Position B (Being at the lowest point, it has the least GPE.)
- Position C (It is not the highest point.)
A: Position A
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: The following diagram shows a the path of a pendulum.  At what point does the pendulum have the highest kinetic energy?
- Position A and C are equivalent. (They are not equivalent in this case.)
- Position A (A has the least.)
- Position B (Correct.)
- Position C (C has more than A, but less than B.)
A: Position B
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: How does the energy required to lift a 20 kg weight 1 m off the floor compare to the energy needed to lift a 40 kg weight 2 m off the floor?
- Lifting the 40 kg weight would require 4 times the energy. (Correct.)
- Lifting the 40 kg weight would require twice the energy. (Energy is proportional to height and mass.)
- Lifting the 40 kg weight would require 3 times the energy. (Energy is proportional to height and mass.)
A: Lifting the 40 kg weight would require 4 times the energy.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: How does the energy of a 1000 kg car moving at 10 m/s compare to the energy of a 2000 kg car moving at 5 m/s?
- The 1000 kg car has twice the energy. (Correct.)
- The 1000 kg car has four times the energy. (It would if the masses were the same.)
- The 2000 kg car has twice the energy. (It would if the velocities were the same.)
A: The 1000 kg car has twice the energy.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: A 50 g piece of metal is pulled out of a boiling water bath and placed into a cup of water (100 g) that is initially at 15 °C.  In the end both metal and water are at 17 °C.  How do the substances change in thermal energy compare?
- The change in thermal energy is identical. (Correct.)
- The metal changes by more. (The metal has a greater temperature change, but the thermal energy change is the same.)
- The water changes by more. (The water has a greater mass, but they have the same thermal energy change.)
A: The change in thermal energy is identical.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: Two waterfalls, A and B, have identical flow rates.  A falls twice as far as B, the water flows no faster at the bottom of the falls compared to the top.  Which will have a greater temperature change?
- A's change in temperature will be twice as big as B's. (Correct.)
- A's temperature change will be four times that of B. (Temperature change is related linearly to energy put in.)
- They will have the same positive temperature change. (A will change more as it falls further.)
- They will have the same negative temperature change. (Potential energy decreases, thermal energy has to increase.)
- Neither will change temperature. (Potential energy is decreasing, thermal energy has to increase.)
A: A's change in temperature will be twice as big as B's.
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: The diagram below shows 3 possible forces that are identical in magnitude on a box that is moving to the right.  Which force would be doing the most amount of work on the box?
- Force B (Correct.)
- Force C (As this is only partially in the direction of motion, it does less work than B.)
- Force A (Since this force is almost perpendicular to the direction of motion, it does little work.)
- All 3 are identical. (The forces are identical, but that does not mean the amount of work they do is, direction matters.)
A: Force B
If right: Your answer is correct.
If wrong: Your answer is incorrect.

Q: How do the amount of works compare for each of the following scenarios.

1. Sliding a 10 kg brick across the floor 1 m using 1 N of force.
2. Sliding a 10 kg brick across the floor 2 m using 1 N of force.
3. Sliding a 10 kg brick across the floor 1 m using 2 N of force.
- Situations 2 and 3 requires the most work. (Correct)
- Situation 1 and 2 require the most work. (Distance also matters.)
- Situation 1 and 3 requires the most work. (Force also matters.)
A: Situations 2 and 3 requires the most work.
If right: Your answer is correct.
If wrong: Your answer is incorrect.