Question

Two electric motors drive two elevators of equal mass in a three-story building 10 meters tall. Each elevator has a mass of 1,000 kg. The first elevator can do this work in 5.0 seconds. Calculate the power output of the first motor.

2.0 x 102 W
2.0 x 103 W
2.0 x 104 W
2.0 x 105 W

Answer 1

2.0 * 10^4 W

Step-by-step explanation:

We will be using these two equations:

`W=m*g*h`

Power = ΔW/Δt

PART 1----------------------

First, we find the work done by the motor.

If you are in the OW physics course, you will already know the value of W from the previous question.

If you don't know W yet, use the equation

`W=m*g*h`

where

W = work;

m = mass of elevator;

g = acceleration due to gravity;

h = height.

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We are given the values for m, g, and h:

m = 1000kg;

g = acceleration due to gravity = 9.8m/s^2;

h = 10m.

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We plug the known values into the equation and solve for W:

`W=m*g*h`

`W = 1000kg * 9.8m/s^2 * 10m`

`W = 9.8 * 10^(4) J`

PART 2----------------------

Now we use the formula

Power = ΔW/Δt

where

ΔW = change in work

Δt = change in time

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We are given a value of t, which is the interval over which the work takes place:

Δt = 5.0 seconds

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Now we can plug in our values for W and t and solve:

`Power = (9.8 * 10^(4) J)/(5.0 sec)`

`Power = 19600W`

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In scientific notation:

1.96 * 10^4 W

Accounting for the maximum of two significant digits:

2.0 * 10^4 W

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Answer 2

2.0 x 104 W

Step-by-step explanation:

Same process as the person above but use significant figures for the problem.