Exam-style CBSE practice questions on What Are the Different Types of Forces? (Exploring Forces). Try each one first, then reveal the correct answer and a step-by-step explanation. Free, from EduLevel — the AI teacher for CBSE.
A force is best described as:
Explanation: A force is simply a push or a pull acting on an object, and it can make the object start moving, stop, speed up, slow down or change shape. It is not a type of energy, and it can be either a push or a pull, not only one of the two.
Which of the following is a non-contact force?
Explanation: Gravitational force acts between objects even when they are far apart and not touching, so it is a non-contact force. Muscular force, frictional force and the push applied to a trolley all need direct contact between surfaces, so they are contact forces.
The force produced by the muscles of our body when we lift, push or pull an object is called:
Explanation: The force applied by the muscles of our body while lifting, pushing or pulling is called muscular force, and it is a contact force because our body must touch the object. Magnetic, electrostatic and gravitational forces do not come from our muscles.
Which force always acts to oppose the motion of one surface moving over another?
Explanation: The frictional force always acts in the direction opposite to the motion, so it opposes one surface sliding over another. Magnetic, muscular and electrostatic forces do not have this property of always opposing sliding motion between surfaces.
A comb rubbed on dry hair can attract small pieces of paper without touching them. This happens because of:
Explanation: When a comb is rubbed on dry hair it becomes electrically charged, and the charged comb then attracts small pieces of paper by the electrostatic force, which acts without contact. It is not magnetic because paper is not a magnetic material, and it is not muscular or frictional.
A ball thrown straight upwards slows down and then falls back to the ground. The force mainly responsible for bringing it back down is:
Explanation: The ball comes back down because the Earth pulls it towards itself with gravitational force, a non-contact force that acts on all objects that have mass. Muscular force acted only while throwing the ball, and friction or electrostatic force are not what pull it back to the ground.
Two bar magnets are brought close together with their north poles facing each other. What will most likely happen?
Explanation: Like poles of magnets repel each other, so when two north poles face each other the magnets push apart. Only unlike poles, a north and a south, attract. This pushing and pulling action of magnets is called the magnetic force, which is a non-contact force.
Why is it easier to slide a box across a smooth floor than across a rough floor?
Explanation: Friction is smaller on smooth surfaces and larger on rough surfaces, so a smooth floor produces less friction and the box slides more easily. A rough floor would create more friction and make sliding harder, which shows that friction does depend on the type of surface.
Gravitational force, electrostatic force and magnetic force are all examples of:
Explanation: Gravitational, electrostatic and magnetic forces can all act on an object without touching it, so they are grouped together as non-contact forces. Contact forces such as muscular force and friction need the surfaces to be in direct contact before they can act.
A metal ball is dropped from a height and falls towards the ground. Which force acts on the falling ball, and what type of force is it?
Explanation: As the ball falls, the Earth pulls it downward with gravitational force, and since gravity acts even when objects are not touching, it is a non-contact force. The option calling gravity a contact force is wrong, and muscular or frictional forces are not what pull the falling ball down.
A plastic scale rubbed with a dry cloth and a bar magnet can both attract certain things without touching them. Which statement about them is correct?
Explanation: A rubbed plastic scale becomes charged and attracts objects by electrostatic force, while a magnet attracts magnetic materials by magnetic force, and both can act without touching, so both are non-contact forces. However, they are two different kinds of force, and they do not need to touch the object to attract it.
A boy pushes a heavy box with his muscular force, but the box does not move at all. Which force acts against his push and keeps the box still?
Explanation: When the boy pushes the box, friction between the box and the ground acts in the opposite direction and can be large enough to stop the box from moving. Gravity pulls the box straight down rather than sideways, so it does not oppose the push, and magnetic and electrostatic forces are not involved here.
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