In what ways the force changes the velocity of a particle?

What is Centripetal force? Write the expression for it?

Write the effects of centrifugal force

A force of 10 N changes velocity of a body from 20 ms^-1 to 40 ms^-1 in 8 seconds. How much force is required to bring about the same change in 4s.

A lift is moving down with an acceleration 5.0 ms^-2. Calculate the percentage change in the weight of a person in the lift