# Power, Work and Force

1. Feb 20, 2016

### GalacticSnipes

1. The problem statement, all variables and given/known data
An elevator cab has a mass of 4600 kg and can carry a maximum load of 1800 kg. If the cab is moving upward at full load at 4.50 m/s, what power is required of the force moving the cab to maintain that speed?

2. Relevant equations
P = W/T
W = F*D
F = M*A
3. The attempt at a solution
P = W/T
P = (F*D)/T
P = ((M*A)*D)/T
P = ((6400*9.8)*D)/T
I don't know what I should enter for D and T

2. Feb 20, 2016

### PhanthomJay

D/T is equal to what ? (using kinematic equations ).

3. Feb 20, 2016

### GalacticSnipes

Distance and Time

4. Feb 20, 2016

### PhanthomJay

Distance divided by time equals _____? (Fill in the blank)

5. Feb 20, 2016

### GalacticSnipes

oh velocity

6. Feb 20, 2016

### GalacticSnipes

so the answer would be 6400*9.8*4.5 = 282240 Watts?

7. Feb 20, 2016

### PhanthomJay

Well, D/T is average or constant speed , which is given.

8. Feb 20, 2016

### GalacticSnipes

constant

9. Feb 20, 2016

### PhanthomJay

Yes. You should round it off to say 280 kW.

10. Feb 20, 2016

### GalacticSnipes

But 282.240 kW is the non rounded answer?

11. Feb 20, 2016

### PhanthomJay

Yes.

12. Feb 20, 2016

ok, thx