An electric winch is used to pull a crate of mass 80 kg up a rough inclined plane at a constant speed of 1.5 m s-1, as shown in the diagram.
The incline is at an angle θ \theta\,θ to the horizontal, where sinθ=0.6\sin\theta = 0.6sinθ=0.6. The coefficient of friction between the crate and the incline is μ=0.25\mu = 0.25μ=0.25.
If the electric winch has an efficiency of 60%, what is the electrical input power required by the winch? (Use g=9.8 m s−2g = 9.8\text{ m s}^{-2}g=9.8 m s−2)
1.57 kW1.57\text{ kW}1.57 kW
1.18 kW1.18\text{ kW}1.18 kW
0.56 kW0.56\text{ kW}0.56 kW
1.67 kW1.67\text{ kW}1.67 kW