Question

Suppose a horizontal force of 20 N is required to maintain a speed of 8 m/s of a 50 kg crate. (a) What is the power of this force? (b) Note that the acceleration of the crate is zero despite the fact that a 20 N force acts on the crate horizontally. What happens to the energy given to the crate as a result of the work done by this 20 N force?

(a) 160 W, converted to heat
(b) 160 W, stored as potential energy
(c) 320 W, converted to kinetic energy
(d) 320 W, dissipated as sound

Answer 1

The force produces a power of 160 W, which is converted to heat due to the opposing frictional force.

Step-by-step explanation:

The power of the force required to maintain the 50 kg crate at a speed of 8 m/s is calculated using the formula

Power (P) = Force (F) × Velocity (v).

Given a force of 20 N and a velocity of 8 m/s, the power P = 20 N × 8 m/s = 160 W.

Since the acceleration of the crate is zero, this means the net force on the crate is zero and therefore the work done by this 20 N force is opposed by an equal magnitude of frictional force.

The energy provided to the crate by the force is thus converted to heat due to friction, making option (a) the correct answer.