Simple question about the power generated by an elevator motor

[Fazza3_uae]

Homework Statement

The motor of an elevator generates 12000 Watts of power when moving the elevator at constant speed of 2 m/s.what is the mass of elevator in kg ...??

There are 5 options for the answer.

a) 500 Kg b) 400 Kg c) 300 Kg d) 240 Kg e) 200 Kg

Homework Equations

P = W/t

The Attempt at a Solution

I tried to solve it like this ..

Power = Work / Time = Force * Displacement / Time = Force * Velocity = m*a*v

So m = P / a*v

where a is the gravitaional acceleration = 9.8 m/s²
v is the constant speed = 2 m/s
P is the power = 12,000 Watts

I simply plugged in the numbers & got 612 Kg which is obviously wrong. Any help would be apprecitaed. Thanks

 

[denverdoc]

It looks good to me, even if you use g=10m/s^2, the answer is 600 and not among the choices.

 

[Fazza3_uae]

thx for ur responding.

So shall i take the nearest answer which is 500 Kg or what ..??

 

[denverdoc]

Go ahead and answer 500, and take your work to the prof. Unless I'm missing something..the question will get kicked out.