Q4.10 Ski Lift (S)

A ski lift raises 100 passengers averaging 70 kg a height of 500 m in 200 s at a constant speed. If one neglects friction, what average power is required of the force producing the lift?
Hide

Hint

How is work related to potential energy? See your notes (Key Point 3.10 and Key Point 3.14)
 

Solution

Reveal
Hide

Solution

The total work done by the force on the ski lift is given by the change in gravitational potential energy of the N people in the lift:

W=Nmgh=3.5×107 J (2 s.f.)

The work is done in 200 seconds, so the power that the lifting force supplies is 175 kW.