# An Elevator and work

[SOLVED] An Elevator and work

## Homework Statement

The loaded cab of an elevator has a mass of 3.0 103 kg and moves 204 m up the shaft in 23 s at constant speed. At what average rate does the force from the cable do work on the cab? Answer in kW.

## Homework Equations

Power is the dot product of the force and velocity
Fnet = ma

## The Attempt at a Solution

I went about this problem by since Power is the dot product of velocity and the force.
The force would be Tension - W = ma and since ma = 0. tension = W = mg so there is your force m*g

then i take 204m/23s to get the velocity of 68 m/s so. . .

mg*68 to give you the power in watts but since they want the velocity in kW, you divide by 1000 to get to that desided amount. . .

PhanthomJay
Homework Helper
Gold Member
Yes. But check your math in calculating velocity.

haha too funny. . .wow do not know where that number came from

ok so I take my force (mg) and multiply it by 8.87 to give me Power . . but is power what I am searching for?

PhanthomJay