Question

Power is defined as the rate of doing work. A cyclist is moving along a flat road. He has a mass of 70 kg and is pedaling to maintain a constant speed of 5 m/s. The cyclist experiences a frictional force of 20 N acting opposite to the direction of motion.

A body of mass 6kg is under a force which causes displacement in it given by S = t²/4 metres where t is time. The work done by the force in 2 seconds is

Assertion: A person working on a horizontal road with a load on his head does no work. Reason: No work is said to be done, if directions of force and displacement of load are perpendicular to each other.

A body of mass 3 kg is under a force, which causes a displacement in it is given by S = t³/3 (in m). Find the work done by the force in first 2 seconds.