A small electric crane raises a load through different heights.
PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Work Energy and Power · Work Energy and Power
Problem
A small electric crane raises a load through different heights.
(i) Derive an expression for the change in gravitational potential energy of a body of mass m when it is raised from height h1 to height h2 above the same reference level.
(ii) Using your expression, find the change in potential energy when a 1.5kg load is lifted from 2m to 10m. Take g=10ms−2.
(iii) If only 60% of the electrical work done by the crane’s motor appears as the gain in potential energy calculated in part (ii), determine (a) the total work done by the motor and (b) the energy lost as heat or sound.
(iv) Suggest one practical way to reduce such energy losses in lifting machines.