Q: 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}$$ in the negative x$-direction, and F_2$ = 10.0\ \mathrm{N} at$$ $$\theta = 11.0^\circ$$ above the negative $$x-$$axis. What is the net force in the $$x-$$direction?

$$F_{\text{net},x} = -1.1\ \mathrm{N}$$

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 and is connected by a string over a frictionless pulley to another block of the same mass, which hangs vertically. 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

The acceleration of an object is inversely proportional to its 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 negative $$x-$$axis. What is the net force in the $$x-$$direction?

Accepted Answer

$$F_{	ext{net},x} = -1.1\ \mathrm{N}$$

Question 5

Which of the following statements about friction is correct?

Accepted Answer

Kinetic friction depends on both the type of surfaces in contact and the normal force.

Question 6

A 28-kg traffic light is suspended by two cables as shown in the diagram, with cable 1 at $$30^\circ$$ and cable 2 at $$60^\circ to $$the horizontal. What is the tension in cable 1?

Accepted Answer

$$T_1 = 274$$\ \mathrm{N}$$

Question 7

Which of the following is true about an object in free fall near Earth's surface?

Accepted Answer

It experiences a constant gravitational force directed downward.

Question 8

A crate of mass $$m = 2.0\ \mathrm{kg} is on a $$frictionless incline at $$	heta = 22^\circ. A $$force $$F is $$applied parallel to the incline, causing the crate to accelerate up the plane at $$1.2\ \mathrm{m/s^2$}. $$What is the normal force on the crate?

Accepted Answer

$$N = 19.1\ \mathrm{N}$$

Question 9

Which of the following statements about tension force is correct?

Accepted Answer

Tension force can be affected by the angle of the rope relative to the horizontal.

Question 10

A car is being towed at constant velocity on a horizontal road using a horizontal chain. Which of the following must be true?

Accepted Answer

The tension in the chain must be equal to the frictional force opposing the motion.

Question 11

Suppose you are playing hockey on perfectly frictionless ice. After you hit the puck and it loses contact with your stick (ignoring air resistance), what happens to the puck?

Accepted Answer

The puck moves at constant velocity.

Question 12

Which of the following is true about static friction?

Accepted Answer

Static friction ceases to exist once the object starts moving.

Question 13

A block of mass $$m is on a $$frictionless surface. Two forces act on it: $$F_1 in $$the negative $$x-$$direction and $$F_2 at an $$angle $$	heta$$ above the negative $$x-$$axis. What is the formula for the normal force $$N on $$the block?

Accepted Answer

$$N = mg - F_2$ \sin 	heta$$

Question 14

Which of the following best describes the relationship between force and acceleration?

Accepted Answer

Force and acceleration are always in the same direction.

Question 15

A crate of mass $$m is on a $$frictionless incline at angle $$	heta. $$What is the formula for the normal force $$N$$ acting on the crate?

Accepted Answer

$$N = mg \cos 	heta$$

Question 16

Which of the following is a correct application of Newton's Third Law?

Accepted Answer

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

Question 17

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

$$T_2 = 158$$\ \mathrm{N}$$

Question 18

A block of mass $$m is $$pulled up a frictionless incline at angle $$	heta$$ with acceleration $$a. $$What is the formula for the applied force $$F$$ parallel to the incline?

Accepted Answer

$$F = mg \sin 	heta + ma$$

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

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