A 50 kg metal container is lifted by an electric hoist.
Calculate the kinetic energy of the 50 kg container when it moves at a speed of 0.4 m/s. Use the equation: kinetic energy=0.5×mass×(speed)2\text{kinetic energy} = 0.5 \times \text{mass} \times (\text{speed})^2kinetic energy=0.5×mass×(speed)2
The 50 kg container is lifted through a height of 12 m. Calculate the gravitational potential energy gained by the container. The gravitational field strength is 10 N/kg.
The hoist lifts the container using an electric motor:
Calculate the efficiency of the motor. Use the equation: efficiency=useful output energy transferinput energy transfer\displaystyle \text{efficiency} = \frac{\text{useful output energy transfer}}{\text{input energy transfer}}efficiency=input energy transferuseful output energy transfer
Explain why the efficiency of the motor is not 100%.
The hoist's gears contain moving parts. An engineer suggests applying grease to these gears. Explain how this will affect the efficiency of the hoist.