An elevator cage of mass is lifted vertically upward through at constant speed by a…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
An elevator cage of mass 1000kg is lifted vertically upward through 12m at constant speed by a steel cable. Take g=9.8ms−2.
(a) Calculate the magnitude of the tension in the cable while the elevator moves at constant speed.
(b) Determine the work done by the tension in the cable during the 12m upward displacement. State the sign of this work.
(c) Determine the work done by the gravitational force on the elevator for the same displacement. State the sign of this work.
(d) Hence find the algebraic sum (net value) of the work done by the two forces and explain why this result is expected for motion at constant speed.