A force can change :

1. the size or shape of a body
2. the state of rest or of motion of a body
3. the dimensions of a body
4. All of the above.

The non-contact force is —

1. force of reaction
2. force due to gravity
3. tension in string
4. force of the friction

A ball placed on a table starts rolling down when the table is tilted. This is an example of :

1. contact force
2. non-contact force
3. both (a) and (b)
4. none of these

When a comb is rubbed on dry hair, it gets charged. This is an example of :

1. Gravitational force
2. normal reaction force
3. magnetic force
4. electrostatic force