Question

Which of the following is a contact force?
A. Gravitational force
B. Friction
C. Electrostatic force
D. Magnetic force

Answer 1

Hint: Contact force is that force which acts on a body by coming in direct physical contact with it. The other type of forces are non-contact forces which are those forces which act from a distance and there is no need for physical contact for the force to act on a body.

Complete step-by-step answer:
The forces in nature can be categorized on the basis of the fact that whether they act on the body by coming in physical contact with the body or not. On the basis of this, we have contact forces and non-contact forces.
Contact forces are those forces which can act on a body only by coming in direct contact with it. Non-contact forces are those forces which do not need to come in contact with the body and act in the body from a distance.

Gravitational force is a non-contact force as it acts between two bodies without the bodies actually coming in contact with each other. For example, the sun attracts the planets without coming in contact with them. Similar is the case with electrostatic force and the magnetic force. Magnetic force is not a contact force because two magnets can attract each other from a distance without coming in contact with each other while the electrostatic force between stationary charges also acts from a distance.
The bodies exhibiting these forces do not need to come in contact with each other and act from a distance.
Friction is a contact force because the bodies need to get in contact with each other in order for the frictional force to act on the bodies.

So, the correct answer is “Option B”.

Note: There four fundamental forces of nature: Gravitational force, electromagnetic force, weak and strong nuclear forces; are all non-contact forces. The non-contact forces can be explained by the standard model of particle physics which says that these forces occur by interchange of certain mediating particles between two bodies.