A person pushes a box across a horizontal surface at a constant speed of 0.5 meter per second. The box has a mass of 40 kilograms, and the coefficient of sliding friction is 0.25. The power supplied to the box by the person is

49 watt

Explanation:

speed, v = 0.5 m/s

mass, m = 40 kg

μ = 0.25

As the block is moving with constant speed so the net acceleration is zero.

It means the applied force is equal to the friction force

F = μ mg = 0.25 x 40 x 9.8

F = 98 N

Power = Force x velocity

P = 98 x 0.5 = 49 Watt

Thus, the power is 49 watt.