Question

A belt,drivenby a motor,moves horizontally with a uniform velocity of 5 m/s. If sand is dropped on the belt at the rate of 5 kg per second,what iextra power does the motor deliver?

Answer 1

The motor has to move the sand as well as the belt. So it has to provide the kinetic energy of the sand. Kinetic energy is 1/2 * m * v^2. And power is just energy per time, and your time is just one second...