Q: A $$5\ \mathrm{kg}$$ box is lifted $$2\ \mathrm{m}$$ vertically. What is the work done against gravity? (Take $$g = 9.8\ \mathrm{m/s^2$})$$

$$W = mgh = 5 \times 9.8 \times 2 = 98\ \mathrm{J}$$

Q: A $$3\ \mathrm{kg}$$ object moving at $$4\ \mathrm{m/s}$$ comes to a stop due to friction after traveling $$6\ \mathrm{m}. $$What is the work done by friction?

$$W = -KE = -\frac{1}{2} \times 3 \times 4^2$ = -24\ \mathrm{J}$$

Q: A runner accelerates at $$2\ \mathrm{m/s^2$}$$ for $$3\ \mathrm{s}$$ from rest. What is the runner's final velocity?

$$v = a t = 2 \times 3 = 6\ \mathrm{m/s}$$

Q: A $$2\ \mathrm{kg}$$ object moves in a circle of radius $$0.5\ \mathrm{m} at$$ $$3\ \mathrm{m/s}. $$What is the centripetal force acting on it?

$$F_c = m \frac{v^2$}{r} = 2 \times \frac{9}{0.5} = 36\ \mathrm{N}$$

Question 1

A car of mass $$m$$ accelerates from rest under a constant net force $$F. $$According to Newton's Second Law, what is the car's acceleration?

Accepted Answer

$$a = \frac{F}{m}$$

Question 2

A ball is swung in a horizontal circle at constant speed. What is the direction of the net force acting on the ball?

Accepted Answer

Toward the center of the circle

Question 3

Which of the following best describes Newton's Third Law?

Accepted Answer

For every action, there is an equal and opposite reaction.

Question 4

A cyclist travels at $$5\ \mathrm{m/s}$$ relative to the ground. If the wind blows at $$3\ \mathrm{m/s}$$ east and the cyclist moves north, what is the magnitude of the cyclist's velocity relative to the wind?

Accepted Answer

$$\sqrt{5^2$ + 3^2$} = \sqrt{34} \approx 5.83\ \mathrm{m/s}$$

Question 5

If a force of $$10\ \mathrm{N} is $$applied to a $$2\ \mathrm{kg}$$ object, what is its acceleration?

Accepted Answer

$$a = \frac{10}{2} = 5\ \mathrm{m/s^2$}$$

Question 6

A car moves in a circle of radius $$r at $$constant speed $$v. $$What is the formula for its centripetal acceleration?

Accepted Answer

$$a_c = \frac{v^2$}{r}$$

Question 7

Which of the following is the correct expression for kinetic energy?

Accepted Answer

$$KE = \frac{1}{2} m v^2$

Question 8

A $$5\ \mathrm{kg}$$ box is lifted $$2\ \mathrm{m}$$ vertically. What is the work done against gravity? (Take $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$W = mgh = 5 	imes 9.8 	imes 2 = 98\ \mathrm{J}$$

Question 9

Which statement about reference frames and observed velocities is correct?

Accepted Answer

Observed velocity depends on the chosen reference frame.

Question 10

The slope of a position vs. time ($$x vs$$. $$t) $$graph represents:

Accepted Answer

Velocity

Question 11

A $$3\ \mathrm{kg}$$ object moving at $$4\ \mathrm{m/s}$$ comes to a stop due to friction after traveling $$6\ \mathrm{m}. $$What is the work done by friction?

Accepted Answer

$$W = -KE = -\frac{1}{2} 	imes 3 	imes 4^2$ = -24\ \mathrm{J}$$

Question 12

Which of the following is the correct formula for work done by a constant force $$F$$ over displacement $$d$$?

Accepted Answer

$$W = F d$$

Question 13

A runner accelerates at $$2\ \mathrm{m/s^2$}$$ for $$3\ \mathrm{s}$$ from rest. What is the runner's final velocity?

Accepted Answer

$$v = a t = 2 	imes 3 = 6\ \mathrm{m/s}$$

Question 14

The area under a velocity vs. time ($$v vs$$. $$t) $$graph represents:

Accepted Answer

Displacement

Question 15

A $$2\ \mathrm{kg}$$ object moves in a circle of radius $$0.5\ \mathrm{m} at$$ $$3\ \mathrm{m/s}. $$What is the centripetal force acting on it?

Accepted Answer

$$F_c = m \frac{v^2$}{r} = 2 	imes \frac{9}{0.5} = 36\ \mathrm{N}$$

Question 16

Which of the following is a correct statement of the Work-Energy Theorem?

Accepted Answer

The net work done on an object equals its change in kinetic energy: $$W_{net} = \Delta KE$$

Question 17

A $$10\ \mathrm{kg}$$ object is moving at $$2\ \mathrm{m/s}. $$What is its kinetic energy?

Accepted Answer

$$KE = \frac{1}{2} 	imes 10 	imes 2^2$ = 20\ \mathrm{J}$$

Question 18

If two objects move in opposite directions at $$4\ \mathrm{m/s}$$ and $$6\ \mathrm{m/s}$$, what is their relative velocity?

Accepted Answer

$$v_{rel} = 4 + 6 = 10\ \mathrm{m/s}$$

Question 19

A $$1\ \mathrm{kg}$$ ball is dropped from a height of $$5\ \mathrm{m}. $$What is its velocity just before hitting the ground? (Ignore air resistance, $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$v = \sqrt{2gh} = \sqrt{2 	imes 9.8 	imes 5} \approx 9.9\ \mathrm{m/s}$$

Physics Exam Study Guide: Newton's Laws, Centripetal Motion, Work & Energy, Relative Velocity, and Vector Motion

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