Question 1

What is a force?

Accepted Answer

A force is a push or pull that can change the motion of an object, measured in newtons (N).

Question 2

What is Newton's First Law of Motion?

Accepted Answer

An object at rest stays at rest, and an object in motion stays in motion unless acted upon by an unbalanced force (inertia).

Question 3

What is the formula for calculating force?

Accepted Answer

Force = mass × acceleration (F = ma).

Question 4

What is the difference between speed and velocity?

Accepted Answer

Speed is how fast an object moves (scalar — magnitude only); velocity is speed with a direction (vector — magnitude and direction).

Question 5

What is Newton's Second Law of Motion?

Accepted Answer

Newton's Second Law states that the acceleration of an object is directly proportional to the net force and inversely proportional to its mass: F = ma.

Question 6

What is Newton's Third Law of Motion?

Accepted Answer

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

Question 7

How does friction affect motion?

Accepted Answer

Friction is a force that opposes motion; it slows objects down and converts kinetic energy into heat.

Question 8

A 10 kg object accelerates at 3 m/s². What is the net force acting on it?

Accepted Answer

F = ma = 10 × 3 = 30 newtons (N).

Question 9

Give an example of Newton's Third Law in everyday life.

Accepted Answer

When you push off a wall, the wall pushes back on you with equal force in the opposite direction. Rocket propulsion is another example — exhaust gases push down, rocket moves up.

Question 10

What is the difference between mass and weight?

Accepted Answer

Mass is the amount of matter in an object (measured in kg, constant everywhere); weight is the gravitational force on an object (measured in N, varies by location).

Question 11

What is the acceleration due to gravity on Earth?

Accepted Answer

The acceleration due to gravity on Earth is approximately 9.8 m/s² (often rounded to 10 m/s²).

Question 12

How would your weight change on the Moon compared to Earth?

Accepted Answer

Your weight on the Moon would be about 1/6 of your Earth weight because the Moon's gravitational pull is much weaker, but your mass stays the same.

Question 13

What is free fall?

Accepted Answer

Free fall is the motion of an object falling under the influence of gravity alone, with no air resistance. All objects in free fall accelerate at the same rate regardless of mass.

Question 14

What are balanced forces?

Accepted Answer

Balanced forces are equal forces acting in opposite directions on an object, resulting in no change in motion (net force = 0).

Question 15

What are unbalanced forces?

Accepted Answer

Unbalanced forces produce a net force greater than zero, causing an object to accelerate (change speed or direction).

Question 16

A book sits on a table. What two forces are balanced?

Accepted Answer

Gravity pulls the book downward, and the normal force from the table pushes upward. These two forces are equal and opposite, so the book remains stationary.

Question 17

A car of mass 1000 kg accelerates from 0 to 20 m/s in 5 seconds. What is the net force?

Accepted Answer

Acceleration = (20-0)/5 = 4 m/s². F = ma = 1000 × 4 = 4000 N.

Question 18

Why does a heavier object not fall faster than a lighter one (ignoring air resistance)?

Accepted Answer

Although gravity exerts more force on a heavier object, it also has more mass. Since a = F/m, the extra force and extra mass cancel out, giving the same acceleration (9.8 m/s²) to all objects.

Question 19

Explain why wearing a seatbelt saves lives using Newton's First Law.

Accepted Answer

In a crash, the car stops suddenly but your body tends to keep moving forward (inertia). The seatbelt applies a force to stop your body, preventing it from hitting the windshield.

Forces and Motion Answer Key

Prior Knowledge Questions

Activity A – Newton's Laws

Activity B – Gravity and Weight

Activity C – Balanced and Unbalanced Forces

Assessment Questions

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