Q: A 2000 kg truck is initially moving at $$v_0 = 30$$\,\text{m/s}$$ and comes to rest (v = 0$$\,\text{m/s}$$) in 5.4 seconds. What is the average acceleration of the truck?

$$a = \frac{0 - 30}{5.4} = -5.56\,\text{m/s}^2$$

Q: Using Newton’s 2nd Law, what is the average force required to stop the 2000 kg truck in 5.4 seconds?

$$F = 2000 \times (-5.56) = -11120\,\text{N}$$

Q: A 1000 kg car and a 2000 kg truck are both acted upon by a net force of $$4000\,\text{N}. $$What is the acceleration of the car?

$$a = \frac{4000}{1000} = 4\,\text{m/s}^2$$

Q: If a 1500 kg car experiences a friction force of $$3000\,\text{N}$$ while moving, what is the acceleration due to friction?

$$a = \frac{3000}{1500} = 2\,\text{m/s}^2$$

Q: A 500 kg object is falling under gravity with air resistance. If the force of gravity is $$4900\,\text{N}$$ and air resistance is $$3500\,\text{N}$$, what is the net force?

$$F_{net} = 4900 - 3500 = 1400\,\text{N}$$

Question 1

According to Newton’s 2nd Law, what is the formula for calculating the net force acting on an object?

Accepted Answer

$$F_{net} = m 	imes a$$

Question 2

A 2000 kg truck is initially moving at $$v_0 = 30$$\,	ext{m/s}$$ and comes to rest (v = 0$$\,	ext{m/s}$$) in 5.4 seconds. What is the average acceleration of the truck?

Accepted Answer

$$a = \frac{0 - 30}{5.4} = -5.56\,	ext{m/s}^2$$

Question 3

Using Newton’s 2nd Law, what is the average force required to stop the 2000 kg truck in 5.4 seconds?

Accepted Answer

$$F = 2000 	imes (-5.56) = -11120\,	ext{N}$$

Question 4

Which statement best describes Newton’s 1st Law of Motion?

Accepted Answer

Objects remain at rest or in uniform motion unless acted upon by a nonzero net force.

Question 5

If two objects of different masses are acted upon by the same force, which will have the greater acceleration?

Accepted Answer

The object with lower mass.

Question 6

A 1000 kg car and a 2000 kg truck are both acted upon by a net force of $$4000\,	ext{N}. $$What is the acceleration of the car?

Accepted Answer

$$a = \frac{4000}{1000} = 4\,	ext{m/s}^2$$

Question 7

Which force always acts in the direction opposite to motion?

Accepted Answer

Friction

Question 8

What happens to the acceleration of an object if the net force acting on it is doubled, assuming mass remains constant?

Accepted Answer

Acceleration is doubled.

Question 9

A skydiver reaches terminal velocity when:

Accepted Answer

The force of gravity equals the force of air resistance.

Question 10

Which equation correctly represents the relationship between net force, mass, and acceleration?

Accepted Answer

$$F_{net} = m 	imes a$$

Question 11

If a 1500 kg car experiences a friction force of $$3000\,	ext{N}$$ while moving, what is the acceleration due to friction?

Accepted Answer

$$a = \frac{3000}{1500} = 2\,	ext{m/s}^2$$

Question 12

Which of the following best describes the effect of friction on a moving object?

Accepted Answer

Friction opposes the object's motion and reduces acceleration.

Question 13

A 500 kg object is falling under gravity with air resistance. If the force of gravity is $$4900\,	ext{N}$$ and air resistance is $$3500\,	ext{N}$$, what is the net force?

Accepted Answer

$$F_{net} = 4900 - 3500 = 1400\,	ext{N}$$

Question 14

Which scenario best illustrates Newton’s 1st Law?

Accepted Answer

A car continues moving at constant speed until brakes are applied.

Question 15

If the net force on an object is zero, what can be said about its acceleration?

Accepted Answer

The object has zero acceleration.

Question 16

A 1200 kg car is stopped from $$20\,	ext{m/s} to$$ $$0\,	ext{m/s} in$$ $$4\,	ext{s}. $$What is the average force applied?

Accepted Answer

$$F = 1200 	imes \frac{0 - 20}{4} = -6000\,	ext{N}$$

Question 17

Which of the following is NOT a type of force discussed in this chapter?

Accepted Answer

Magnetic Force

Question 18

If an object is in free fall, which forces are acting on it?

Accepted Answer

Only gravity

Question 19

A 2500 kg truck is acted upon by a net force of $$5000\,	ext{N}. $$What is its acceleration?

Accepted Answer

$$a = \frac{5000}{2500} = 2\,	ext{m/s}^2$$

Question 20

Which of the following best describes terminal velocity?

Accepted Answer

The velocity at which the net force on a falling object is zero.

Newton’s Second Law of Motion: Forces, Acceleration, and Applications

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