PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A winch pulls a crate along a horizontal surface. A timer connected to the winch records that the mechanical power it delivers to the crate increases uniformly from 0W at t=0s to 100W at t=10s.
Neglect friction and assume that all power delivered goes into increasing the crate’s kinetic energy.
(a) Determine the total work done on the crate during the 10-s interval.
(b) Calculate the average power delivered to the crate over the same interval and compare it to the arithmetic mean of the initial and final power values.
(c) If the crate’s speed at t=0s was negligible, determine its speed at t=10s given that the crate has mass m=25kg. Express your answer to two significant figures.