Question 1

According to Newton's first law, what will happen to an object in motion if no net force acts upon it?

Accepted Answer

It will continue moving in a straight line at constant speed.

Question 2

A sled is moving across a frictionless surface. What force is required to keep it moving at constant velocity?

Accepted Answer

No force is required.

Question 3

Which of the following is a correct statement of Newton's second law?

Accepted Answer

$$F_{net} = m a$$

Question 4

A 2 kg block is pulled by a horizontal force of 10 N on a frictionless surface. What is its acceleration?

Accepted Answer

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

Question 5

Which of the following is NOT a contact force?

Accepted Answer

Gravitational force

Question 6

A car of mass 1500 kg is being towed by a rope at a 20° angle to the horizontal. If the car accelerates at $$2 \ \mathrm{m/s^2$}$$ and friction opposes with 120 N, what is the horizontal component of the tension in the rope?

Accepted Answer

$$T_x = 3000 \ \mathrm{N}$$

Question 7

Which force always acts perpendicular to the surface of contact?

Accepted Answer

Normal force

Question 8

A block hangs from a rope and accelerates upward at $$2 \ \mathrm{m/s^2$}. If $$its weight is 980 N, what is the tension in the rope?

Accepted Answer

$$T = 1180 \ \mathrm{N}$$

Question 9

Which statement best describes Newton's third law?

Accepted Answer

For every force, there is an equal and opposite force acting on a different object.

Question 10

A box is pulled by two ropes with forces $$F_1 = 10$$ \ \mathrm{N}$$ east and F_2$ = 5 \ \mathrm{N}$$ north. What is the magnitude of the net force?

Accepted Answer

$$F_{net} = \sqrt{125} \approx 11.2 \ \mathrm{N}$$

Question 11

Which force opposes the motion of an object sliding across a surface?

Accepted Answer

Kinetic friction

Question 12

A rocket expels gas molecules at high speed. According to Newton's laws, what is the direction of the force on the rocket?

Accepted Answer

Opposite direction to the expelled gas

Question 13

Which of the following is the correct SI unit for force?

Accepted Answer

Newton

Question 14

A 5 kg object is acted upon by a net force of 20 N. What is its acceleration?

Accepted Answer

$$a = 4 \ \mathrm{m/s^2$}$$

Question 15

Which force keeps an object 'stuck' on a surface and prevents it from moving?

Accepted Answer

Static friction

Question 16

A ball rolls down an incline and then onto a horizontal ramp. Neglecting air resistance, what force acts on the ball as it moves along the horizontal ramp?

Accepted Answer

Only the gravitational force acting vertically downward

Question 17

Which of the following is a long-range force?

Accepted Answer

Gravitational force

Question 18

When drawing a free body diagram, what does each arrow represent?

Accepted Answer

The direction and magnitude of a force acting on the object

Question 19

A 10 kg box is at rest on a horizontal surface. What is the magnitude of the normal force acting on it?

Accepted Answer

$$F_N = 98 \ \mathrm{N}$$

Question 20

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

Accepted Answer

Acceleration is directly proportional to force and inversely proportional to mass.

Forces and Motion: Newton's Laws and Problem Solving

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