Two persons manage to push a motorcar of mass 1200 kg at a uniform velocity along a level road, the same motorcar can be pushed by three persons to produce an acceleration of `0.2 m s^-2`. With what force does each person push the motorcar? (Assume that all persons push the motorcar with the same muscular effort.)

A motorcar of mass 1200 kg is moving along a straight line with a uniform velocity of 90 km/h. Its velocity is slowed down to 18 km/h in 4 s by an unbalanced external force. Calculate the acceleration and change in momentum. Also calculate the magnitude of the force required.

Two objects, each of mass 1.5 kg, are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 m s^-1 before the collision during which they stick together. What will be the velocity of the combined object after collision?

A truck starts from rest and accelerates* uniformly at 2.0ms*2. At f = 10 s, a stone is dropped by a person standing on the top of the truck (6 m high from the ground). What are the (a) velocity, and (b) acceleration of the stone at f = 11 s? (Neglect air resistance:)

A person trying to lose weight (dieter) lifts a 10 kg mass, one , thousand times, to a height of 0.5 m each time. Assume that the potential energy lost each time she lowers the mass is dissipated, (a) How much work does she do against the gravitational force? (b) Fat supplies 3.8 xx 10^7 J of energy per kilogram which is converted to mechanical energy with a 20% efficiency rate. How much fat will the dieter use up?