Question

A motor is powered by battery with an energy capacity of E_{battery} =E​battery​​=1 WHr (1 WHr = 3600 Joules). The motor sit at the topic of a concrete ramp and is connected to a cable that is used to pull a 70.4-kg wood crate up the concrete ramp with a coefficient of kinetic friction of 0.304 and an angle of 50.5 ^\circ​∘​​ above the horizontal. Assume that the net energy efficiency of the battery-powered motor is only \varepsilon = 0.25ε=0.25 for this application. (this is the fraction of the stored energy that is converted into useful mechanical work; the rest is lost as heat in the motor or battery). The wood crate is initially stationary at the bottom of the ramp. How far up the ramp can the motor pull the crate before the initially-fully-charged battery is completed drained?

Answer 1