Question 1

A boulder of mass $$m$$ starts from rest and rolls down a hill of height $$h$$, as shown in the first image. Neglecting friction, what is the speed of the boulder at the bottom of the hill?

Accepted Answer

$$v = \sqrt{2gh}$$

Question 2

A stack of plates is precariously balanced in a cabinet (see the second image). If a plate falls and hits a hard floor, which factor most affects the force of impact?

Accepted Answer

The time of impact with the ground

Question 3

A ball of mass $$1\ \mathrm{kg}$$ moving at $$1\ \mathrm{m/s}$$ hits a wall and bounces back with the same speed in the opposite direction. What is the impulse delivered to the ball?

Accepted Answer

$$2\ \mathrm{kg\cdot m/s}$$

Question 4

Refer to the force vs. time graph (fourth image). What does the area under the curve represent?

Accepted Answer

Impulse

Question 5

A cannon fires a cannonball (see the fifth image). According to the law of conservation of momentum, what happens to the cannon when the ball is fired?

Accepted Answer

The cannon recoils with momentum equal in magnitude and opposite in direction to the ball's momentum

Question 6

A worker lifts a 50 N bag to the first, second, and third floors as shown in images 6, 7, and 8. Which scenario requires the most work?

Accepted Answer

Lifting to the third floor

Question 7

A person pushes against a stationary wall for several minutes (see image 9). How much work is done on the wall?

Accepted Answer

$$0\ \mathrm{J}$$

Question 8

If you push a cart with a constant force $$F$$ for a distance $$d$$, and then push it twice as far with the same force, how does the work done compare?

Accepted Answer

The work is twice as much

Question 9

A 2 kg mass has 30 J of gravitational potential energy with respect to the ground. Approximately how high is it above the ground? (Use $$g = 10\ \mathrm{m/s^2$})$$

Accepted Answer

$$1.5\ \mathrm{m}$$

Question 10

A car moves twice as fast as an identical car. Compared to the slower car, the faster car has:

Accepted Answer

4 times the kinetic energy

Question 11

Which equation best expresses the work-energy theorem?

Accepted Answer

$$F d = \Delta \left( \frac{1}{2} m v^2$ \right)$$

Question 12

A machine is 30% efficient. What does this mean?

Accepted Answer

30% of the energy input is converted to useful work

Question 13

A ball is moving at $$3\ \mathrm{m/s}$$ and has a momentum of $$12\ \mathrm{kg\cdot m/s}. $$What is the ball's mass?

Accepted Answer

$$4\ \mathrm{kg}$$

Question 14

A dish falls from a cabinet and hits the ground. Which of the following will increase the impulse experienced by the dish?

Accepted Answer

Increasing the time of impact

Question 15

A freight train triples its mass but keeps the same speed. What happens to its momentum?

Accepted Answer

It triples

Question 16

Which of the following best describes the law of conservation of momentum?

Accepted Answer

In the absence of external forces, the total momentum of a system remains unchanged

Question 17

A car with momentum must also have:

Accepted Answer

Kinetic energy

Question 18

If you push a crate horizontally with $$100\ \mathrm{N}$$ across a $$10\ \mathrm{m}$$ factory floor, how much work do you do?

Accepted Answer

$$1000\ \mathrm{J}$$

Question 19

A ball is placed at different heights as shown in the image with three ramps. Which ball has the greatest gravitational potential energy?

Accepted Answer

The ball at the highest vertical position

Momentum, Impulse, Energy, and Efficiency: Study Guide for Physics with Calculus

Guida di studio - Domande di pratica

Study guide - Flashcard