47. The total work is the sum of the work done by gravity on the elevator, the work done by gravity on the counterweight, and the work done by the motor on the system: WT= We+ Wc+ Ws.Since the elevator moves at constant velocity, its kinetic energy does not change and according to the work-kinetic energy theorem the total work done is zero. This means We+Wc+ Ws= 0. The elevator moves upward through 54 m, so the work done by gravity on it is 25(1200 kg)(9.80 m/s )(54 m)6.35 10 J.eeWmgd=−
This is the end of the preview. Sign up
access the rest of the document.
This note was uploaded on 05/17/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.