Question

Assertion: A person lifting a heavy object does more work when lifting it quickly compared to slowly. Reason: Work done is dependent on the speed at which the lifting occurs.

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: Torque on a body can be zero even if there is a net force on it. R: Torque and force on a body are always perpendicular.

A: A couple does not exert a net force even though it exerts a torque. R: Couple is a pair of two forces with equal magnitude but opposite directions acting simultaneously on a body in different lines of action.