Forces Questions & MCQ — Free Practice with Answers

What is a force?

A force is a push or a pull. You cannot see a force, but you can see its effects on objects. When you kick a ball, you push it with your foot. When you open a drawer, you pull it towards you. Forces are always exerted on an object by another object — we say “a force acts on the ball”, not “the ball has force”.

Effects of forces

A force can have several effects on an object. A force can move a stationary object (pushing a toy car makes it move). A force can speed up a moving object (pedalling harder on a bicycle). A force can slow down a moving object (friction between brakes and the wheel). A force can change the direction of a moving object (hitting a shuttlecock with a racket). A force can stop a moving object (a goalkeeper catching a ball). A force can also change the shape of an object (squeezing a sponge or stretching a rubber band).

Frictional force

Frictional force is a force that opposes or resists the movement of one surface past another. When you push a book across a table, friction acts in the opposite direction to slow the book down. There is more friction between an object and a rough surface than between an object and a smooth surface. This is why a ball rolls a shorter distance on a carpet than on a polished floor. Friction can be useful (grip on shoes prevents slipping) or a hindrance (friction slows down moving parts in machines).

Gravitational force

Gravitational force is a force that pulls objects towards the Earth. It is the reason why objects fall to the ground when dropped and why we stay on the surface of the Earth. Objects have weight because of the gravitational force acting on them. Weight is a measure of the gravitational force pulling an object towards the Earth. All objects, regardless of their mass, are pulled downwards by gravity.

Elastic spring force and magnetic force

Elastic spring force is the force exerted by a stretched or compressed spring (or elastic material) as it tries to return to its original shape. When you stretch a rubber band, the elastic spring force pulls back on your fingers. The more you stretch or compress it, the greater the elastic spring force. Magnetic force is the force exerted by magnets. It can attract magnetic materials (such as iron, steel, nickel, and cobalt) or repel another magnet. Magnetic force is a non-contact force — it can act through air and even through some materials without touching the object.

“Heavier objects fall faster than lighter objects.” In the absence of friction, all objects fall at the same rate regardless of their mass. Gravitational force acts on all objects equally in this sense. In everyday life, lighter objects like feathers appear to fall more slowly because of friction with the air, not because gravity pulls them less. If you dropped a heavy ball and a light ball of the same size from the same height, they would reach the ground at almost the same time.

“Friction is always bad and should be reduced.” Friction is not always unwanted. Without friction, we would not be able to walk (our shoes would slip on the ground), hold objects (they would slide out of our hands), or write (a pen would slide across paper without leaving a mark). Friction is only a problem when it slows things down unnecessarily, such as in machine parts. In many situations, we deliberately increase friction — for example, the grooves on shoe soles provide better grip on wet surfaces.

“A moving object always has a force pushing it forward.” An object can continue moving even after the force that started it has stopped. When you kick a ball, your foot pushes it to start moving, but once the ball leaves your foot, no forward force is acting on it. The ball eventually stops because of frictional force acting against its motion, not because the pushing force runs out.

“Mass and weight are the same thing.” Mass and weight are different. Mass is the amount of matter in an object and is measured in grams or kilograms. Mass does not change no matter where the object is. Weight is the gravitational force pulling the object towards the Earth and is a measure of how heavy the object feels. An object on the Moon would have the same mass but a different weight because the Moon's gravitational pull is weaker than the Earth's.