I ) Give one word for the following :- 1. The net force which causes some effect on an object-

2. A device in which ball bearings are used to reduce friction-

II ) Select the correct option :-

1. Buring of a meteor in the atmosphere is due to .
a) Frictional force
b) Magnetic force
c) gravitational force

2. The deep groves in the tyres of a tracter-
a) increase friction
b) decrease friction
c) make it stable

3. The force which an object exerts on any other object is .
a) gravitational force
b) magnetic force
c) electrostatic force
d) frictional force

​