Common Forces In Mechanics - Practice Questions & MCQ

1. Gravitational force (Weight):-

• Definition- Force with which earth attracts an object.

• It always acts towards the center of the earth

• It is denoted by W=mg, where m=mass of the body and g= acceleration due to gravity.

2.    Normal Reaction(N or R):-

• Definition- A force which is perpendicular to the surface in contact or point of contact of two

Surfaces.

3.    Tension(T):-

• Force exerted by taut string, rope or chain against pulling force.

• Its unit is also Newton.

• It acts away from the point of contact.

• Tension remains the same as long as the string is the same only in case of a massless string.

4.    Spring Force:-

• Spring force is also called restoring force.

•  

           where k is the spring constant and its unit is N/m and x is net elongation or compression in the spring.

• Here -ve sign is because the force exerted by the spring is always in the opposite direction to the displacement. 

5.    Friction:-

• Friction is the force which acts in the direction opposite to relative motion.

• It acts between two surfaces in contact.