Q: A block of mass $$m is at $$rest on an inclined plane that makes an angle $$\theta$$ with the horizontal. The coefficient of static friction is $$\mu_s. $$What is the maximum angle $$\theta_{max}$$ before the block starts to slide?

$$\theta_{max} = \arctan(\mu_s)$$

Question 1

Which of the following best describes Newton's First Law of Motion?

Accepted Answer

An object at rest remains at rest, and an object in motion remains in motion at constant velocity unless acted on by a nonzero net force.

Question 2

A 5 kg box is pulled across a horizontal surface with a force of 20 N. If the coefficient of kinetic friction is $$\mu_k = 0.2$$, what is the acceleration of the box? (Take $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$1.2\ \mathrm{m/s^2$}$$

Question 3

Which of the following is NOT a contact force?

Accepted Answer

Gravitational force

Question 4

A block of mass $$m is at $$rest on an inclined plane that makes an angle $$	heta$$ with the horizontal. The coefficient of static friction is $$\mu_s. $$What is the maximum angle $$	heta_{max}$$ before the block starts to slide?

Accepted Answer

$$	heta_{max} = \arctan(\mu_s)$$

Question 5

A 10 kg object is suspended by a rope. What is the tension in the rope if the object is at rest? (Take $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$98\ \mathrm{N}$$

Question 6

Which of the following statements about friction is correct?

Accepted Answer

The force of static friction can vary up to a maximum value.

Question 7

A 2 kg block is pushed with a force of 10 N on a frictionless surface. What is its acceleration?

Accepted Answer

$$5\ \mathrm{m/s^2$}$$

Question 8

Two forces, $$F_1 = 3$$\ \mathrm{N}$$ and F_2$ = 4\ \mathrm{N}$$, act perpendicularly on an object. What is the magnitude of the net force?

Accepted Answer

$$5\ \mathrm{N}$$

Question 9

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

Accepted Answer

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

Question 10

A 350 kg airboat experiences a net force of 770 N. What is its acceleration?

Accepted Answer

$$2.2\ \mathrm{m/s^2$}$$

Question 11

A block is being pulled up a ramp at constant speed. Which statement is true about the forces acting on the block?

Accepted Answer

The net force is zero.

Question 12

Which of the following is the correct expression for the gravitational force between two masses $$m_1$$ and $$m_2$$ separated by a distance $$r$$?

Accepted Answer

$$F = G \dfrac{m_1$ m_2$}{r^2$}$$

Question 13

A 4 kg block and a 7 kg ball are connected by a string over a frictionless pulley. The coefficient of kinetic friction between the block and the surface is $$\mu_k = 0.3. $$What is the acceleration of the system? (Take $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$1.68\ \mathrm{m/s^2$}$$

Question 14

Which of the following is a correct statement about normal force?

Accepted Answer

It acts perpendicular to the surface of contact.

Question 15

A 2 kg object is dropped from rest. Neglecting air resistance, what is the net force acting on the object as it falls? (Take $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$19.6\ \mathrm{N}$$ downward

Question 16

A person pushes a box with a force of 50 N. The box does not move. If the coefficient of static friction is $$\mu_s = 0.6$$ and the box weighs 100 N, what is the maximum static friction force?

Accepted Answer

$$60\ \mathrm{N}$$

Question 17

Which of the following is a vector quantity?

Accepted Answer

Force

Question 18

A 1 kg object is acted on by two perpendicular forces: $$F_1 = 6$$\ \mathrm{N}$$ and F_2$ = 8\ \mathrm{N}. $$What is the magnitude of the acceleration?

Accepted Answer

$$10\ \mathrm{m/s^2$}$$

Question 19

Which of the following best describes inertia?

Accepted Answer

The tendency of an object to resist changes in its motion.

Forces and Newton’s Laws of Motion: Comprehensive Study Notes

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