Question 1

Which of the following statements best describes mass?

Accepted Answer

Mass is a scalar quantity because it has magnitude but no direction.

Question 2

A 3 kg object is on Earth. What is its weight? (Use $$g = 9.81\ \mathrm{m/s^2$})$$

Accepted Answer

$$29.43\ \mathrm{N}$$

Question 3

A 5 kg cart accelerates at $$2\ \mathrm{m/s^2$}. $$What is the net force acting on it?

Accepted Answer

$$10\ \mathrm{N}$$

Question 4

If you push a bike forward while it is already moving forward, what happens to its acceleration?

Accepted Answer

Acceleration increases because the force is in the same direction as motion.

Question 5

A sled slides to the right, but wind blows to the left. What happens to its acceleration?

Accepted Answer

Acceleration decreases because the wind opposes the sled's motion.

Question 6

If the mass of an object doubles but the acceleration remains the same, what must happen to the force applied?

Accepted Answer

The force must double.

Question 7

A 2 kg ball requires $$10\ \mathrm{N} to $$accelerate at $$5\ \mathrm{m/s^2$}. $$What force is needed for a 4 kg ball to achieve the same acceleration?

Accepted Answer

$$20\ \mathrm{N}$$

Question 8

Which object has greater inertia: a 1 kg rock or a 5 kg rock?

Accepted Answer

The 5 kg rock, because it has more mass.

Question 9

Why is inertia tied to mass?

Accepted Answer

Objects with more mass resist changes in motion more.

Question 10

A skydiver reaches terminal velocity. What is the acceleration at this point?

Accepted Answer

$$0\ \mathrm{m/s^2$}$$

Question 11

At terminal velocity, what is the relationship between air resistance and weight?

Accepted Answer

Air resistance equals weight.

Question 12

A 3 kg object falls and reaches terminal velocity. What is the air resistance force acting on it?

Accepted Answer

$$29.43\ \mathrm{N}$$

Question 13

A 2 kg ball falls and experiences $$10\ \mathrm{N} of $$air resistance. What is its acceleration? (Use $$g = 9.81\ \mathrm{m/s^2$})$$

Accepted Answer

$$4.81\ \mathrm{m/s^2$}$$

Question 14

Why is the acceleration of a falling object lower when air resistance is present?

Accepted Answer

Air resistance opposes gravity, reducing the net force and thus acceleration.

Question 15

Which type of friction is greater: static or sliding?

Accepted Answer

Static friction is greater because it resists starting motion.

Question 16

Why is it harder to push a box from rest than to keep it sliding?

Accepted Answer

Because static friction is greater than sliding friction.

Question 17

A box has a mass of $$2\ \mathrm{kg}. $$What is its weight on the Moon if lunar gravity is $$1.62\ \mathrm{m/s^2$}$$?

Accepted Answer

$$3.24\ \mathrm{N}$$

Question 18

A 1 kg ball needs $$10\ \mathrm{N} to $$accelerate at $$10\ \mathrm{m/s^2$}. $$What force is needed for a 2 kg ball to accelerate at $$10\ \mathrm{m/s^2$}$$?

Accepted Answer

$$20\ \mathrm{N}$$

Question 19

Which of the following best explains why weight changes on the Moon but mass does not?

Accepted Answer

Weight depends on gravity, which is different on the Moon, but mass is an intrinsic property.

Question 20

A feather falls and eventually stops accelerating. What is the reason for this?

Accepted Answer

Air resistance balances gravity, resulting in zero net force.

Newton’s Second Law and Forces in Motion – Study Notes

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