Question 1

Which of the following statements about inertia is correct?

Accepted Answer

An object's inertia depends on its mass.

Question 2

A block of mass $$0.30\ \mathrm{kg}$$ slides on a horizontal table connected by a string to another block of the same mass hanging vertically (see image 1). The hanging block falls $$0.80\ \mathrm{m} in$$ $$2.5\ \mathrm{s}. $$What is the coefficient of kinetic friction $$\mu_k$$ between the table and the sliding block?

Accepted Answer

$$\mu_k = 0.13$$

Question 3

Which of the following is true about the acceleration of an object according to Newton's Second Law?

Accepted Answer

Acceleration depends on both the net force and the mass.

Question 4

A block of mass $$m = 11.0\ \mathrm{kg}$$ rests on a frictionless surface. Two forces act on it: $$F_1 = 11.5$$\ \mathrm{N}$$ in the negative x$-direction, and F_2$ = 10.0\ \mathrm{N} at$$ $$	heta = 11.0^\circ$$ above the horizontal (see image 2). What is the net force in the $$x-$$direction?

Accepted Answer

$$F_{net,x} = -2.7\ \mathrm{N}$$

Question 5

If the direction of an object's motion changes, which of the following is affected?

Accepted Answer

Both its velocity and its acceleration.

Question 6

A 28-kg traffic light is suspended by two cables at $$30^\circ$$ and $$60^\circ to $$the horizontal (see image 3). What is the tension in cable 1?

Accepted Answer

$$T_1 = 158$$\ \mathrm{N}$$

Question 7

A crate of mass $$m = 2.0\ \mathrm{kg} is on a $$frictionless inclined plane at angle $$	heta ($$see image 4). If the crate accelerates up the plane at $$1.2\ \mathrm{m/s^2$}$$, what is the normal force acting on the crate?

Accepted Answer

$$F_N = mg \cos 	heta$$

Question 8

Which of the following statements about free fall is correct?

Accepted Answer

An object in free fall experiences only gravitational force.

Question 9

Once an object starts moving, which type of friction acts on it?

Accepted Answer

Kinetic friction.

Question 10

A car is being towed at constant velocity on a horizontal road using a horizontal chain. What must the tension in the chain be?

Accepted Answer

Equal to the force of friction opposing the motion.

Question 11

Suppose you are playing hockey on an ice surface with no friction. After you hit the puck and it loses contact with your stick, what happens to its acceleration?

Accepted Answer

The puck moves at constant velocity.

Question 12

Kinetic friction depends on which factors?

Accepted Answer

The type of surfaces in contact and the normal force.

Question 13

In order to get an object moving, you must push harder on it than it pushes back on you. Which law does this statement violate?

Accepted Answer

Newton's Third Law.

Question 14

The tension force in a rope can be affected by which of the following?

Accepted Answer

The angle of the rope relative to the horizontal.

Question 15

A block of mass $$m = 11.0\ \mathrm{kg} is $$acted upon by $$F_1 = 11.5$$\ \mathrm{N}$$ (negative x$-direction) and F_2$ = 10.0\ \mathrm{N} at$$ $$	heta = 11.0^\circ$$ above the horizontal. What is the acceleration of the block in the $$x-$$direction?

Accepted Answer

$$a_x = -0.25\ \mathrm{m/s^2$}$$

Question 16

A 28-kg traffic light is suspended by two cables at $$30^\circ$$ and $$60^\circ to $$the horizontal. What is the tension in cable 2?

Accepted Answer

$$T_2 = 274$$\ \mathrm{N}$$

Question 17

A crate of mass $$m = 2.0\ \mathrm{kg} is on a $$frictionless inclined plane at angle $$	heta. If $$the crate accelerates up the plane at $$1.2\ \mathrm{m/s^2$}$$, what is the magnitude of the applied force $$F$$?

Accepted Answer

$$F = m a + m g \sin 	heta$$

Newton's Laws, Forces, and Friction: Step-by-Step Physics Guidance

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