A force which acts for a small time and also varies with time is called:
Electrostatic force
Centripetal force
Electromagnetic force
Impulsive force
A force which acts for a small time and also varies with time is called Impulsive force.
It is said that there is no shield found which can stop gravity acting. But there is a force called centripetal force which acts between planets so that they don't bump into each other. So is'nt it that centripetal force is a shield to gravity?
A car of mass m moving along a circular track of radius r with a speed v which varies with time t as v=kt, k being a constant. Then,