How Much Work and Power Does an Elevator Motor Need?

AI Thread Summary
The discussion focuses on calculating the work and power required for a 4500kg elevator moving upward 10 meters in 3.8 seconds. The initial calculation incorrectly assumed acceleration, while the correct approach considers the elevator moving at constant velocity, requiring a force equal to its weight. The proper formula for work is W = (mass)(gravity)(distance), leading to a work value of 441,000 joules. Consequently, the minimum power required can be calculated by dividing work by time. This clarification emphasizes the importance of accounting for gravitational forces in such calculations.
NewJersey
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A 4500kg elevator moves upward 10m in a times of 3.8s
a) The minimum work done by the motor is
b) The minimum motor power rewuired is

a W=F* X
So F= m*a , that 4500kg * 3.8s = 171,000

therfore P= 171,000/10 = 17,100

Is this right?
 
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You have the right equation for work however since the elevator is moving at a constant velocity and its direction doesn't change, there actually is no acceleration present.

Something to consider is that because the elevator is moving in the y-direction, gravity also has an affect on the forces that are acting on it. Therefore, to be able to move vertically, the elevator has to have a force equal to or greater than its weight (not mass). Weight is equal to its mass times gravity. Therefore, your equation would look like this: W = (mass)(gravity)(distance travel)

Hope this sets you on the right track.
 
So it will be W= (4500kg)(9.8)(10) = 441,000
 
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