Question 1

A 10 kg box rests on a horizontal floor. The coefficient of static friction between the box and the floor is 0.5. What is the minimum horizontal force required to start moving the box?

Accepted Answer

$$50\ \mathrm{N}$$

Question 2

A 2 kg object is moving in a circle of radius $$0.5\ \mathrm{m} at a $$constant speed of $$4\ \mathrm{m/s}. $$What is the magnitude of the net force acting on the object?

Accepted Answer

$$16\ \mathrm{N}$$

Question 3

A student lifts a $$15\ \mathrm{kg}$$ backpack vertically upward $$2\ \mathrm{m} at $$constant speed. What is the work done by the student against gravity?

Accepted Answer

$$294\ \mathrm{J}$$

Question 4

A block slides down a frictionless incline of height $$h. If it $$starts from rest, what is its speed at the bottom?

Accepted Answer

$$\sqrt{2gh}$$

Question 5

A $$0.5\ \mathrm{kg}$$ ball is attached to a string and swung in a horizontal circle of radius $$1.5\ \mathrm{m} at a $$speed of $$3\ \mathrm{m/s}. $$What is the tension in the string?

Accepted Answer

$$9\ \mathrm{N}$$

Question 6

A $$2\ \mathrm{kg}$$ block slides $$5\ \mathrm{m}$$ across a rough surface with a coefficient of kinetic friction $$\mu_k = 0.2. $$How much work is done by friction?

Accepted Answer

$$-19.6\ \mathrm{J}$$

Question 7

A spring with spring constant $$k = 400\ \mathrm{N/m} is $$compressed $$0.1\ \mathrm{m}. $$What is the elastic potential energy stored in the spring?

Accepted Answer

$$2\ \mathrm{J}$$

Question 8

A $$3\ \mathrm{kg}$$ object is moving at $$6\ \mathrm{m/s}. $$What is its kinetic energy?

Accepted Answer

$$54\ \mathrm{J}$$

Question 9

A $$10\ \mathrm{kg}$$ box is pulled up a $$30^\circ$$ incline ($$\mu_k = 0.1) at $$constant speed for $$4\ \mathrm{m}. $$What is the total work done by the person pulling the box?

Accepted Answer

$$256\ \mathrm{J}$$

Question 10

A $$0.2\ \mathrm{kg}$$ apple falls from a height of $$5\ \mathrm{m}. $$Ignoring air resistance, what is its speed just before hitting the ground?

Accepted Answer

$$10\ \mathrm{m/s}$$

Question 11

A $$60\ \mathrm{kg}$$ person runs up a $$3\ \mathrm{m}$$ high flight of stairs in $$4\ \mathrm{s}. $$What is the average power output?

Accepted Answer

$$441\ \mathrm{W}$$

Question 12

Which of the following is a correct statement about conservative and nonconservative forces?

Accepted Answer

Friction is a nonconservative force because the work it does depends on the path taken.

Question 13

A $$5\ \mathrm{kg}$$ block is released from rest at the top of a $$2\ \mathrm{m}$$ high frictionless ramp. What is its speed at the bottom?

Accepted Answer

$$6.26\ \mathrm{m/s}$$

Question 14

A $$1.5\ \mathrm{kg}$$ cart is pushed with a constant force of $$6\ \mathrm{N}$$ over a distance of $$3\ \mathrm{m}$$ along a straight, frictionless track. What is the final speed of the cart if it starts from rest?

Accepted Answer

$$4.9\ \mathrm{m/s}$$

Question 15

A $$0.3\ \mathrm{kg}$$ ball is dropped from a height of $$10\ \mathrm{m}. If$$ $$6\ \mathrm{J} of $$energy is lost to air resistance, what is the speed of the ball just before it hits the ground?

Accepted Answer

$$6.4\ \mathrm{m/s}$$

Question 16

A $$2\ \mathrm{kg}$$ block is attached to a spring ($$k = 200\ \mathrm{N/m}) $$and compressed $$0.2\ \mathrm{m}$$ from equilibrium. If released from rest, what is its speed as it passes through equilibrium?

Accepted Answer

$$4\ \mathrm{m/s}$$

Question 17

A $$1\ \mathrm{kg}$$ object moves in a circle of radius $$2\ \mathrm{m} at a $$constant speed. If the net force acting on it is $$8\ \mathrm{N}$$, what is its speed?

Accepted Answer

$$4\ \mathrm{m/s}$$

Question 18

A $$10\ \mathrm{kg}$$ box is pushed across a horizontal floor with a force of $$60\ \mathrm{N} at an $$angle of $$30^\circ$$ below the horizontal. The coefficient of kinetic friction is $$0.2. $$What is the acceleration of the box?

Accepted Answer

$$2.1\ \mathrm{m/s^2$}$$

Question 19

A $$0.5\ \mathrm{kg}$$ puck slides on ice and comes to rest after $$10\ \mathrm{m}$$ due to friction. If the coefficient of kinetic friction is $$0.05$$, what was its initial speed?

Accepted Answer

$$3.13\ \mathrm{m/s}$$

Physics Exam Review: Newton's Laws, Applications, Work, and Energy (Chapters 4–7)

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