# Work problem in watts

1. Nov 1, 2006

### wakejosh

not sure how to solve this, having trouble finding the equation I need in my book. any help is appreciated. thanks in advance.

A 60 kg woman runs up a flight of stairs having a rise of 4.0 m in
a time of 6.0 s. What
average power did she supply?

2. Nov 1, 2006

### geoffjb

Find the equation for power, and work back from that.

3. Nov 1, 2006

### wakejosh

and another one:

A horizontal force of 100 N is applied to move a 45 kg cart across
a 9.0 m level surface.
What amount of work is done by the 100 N force?

now with this one do I just do 100 N * 9.0 M = 900 J ? is this correct?

4. Nov 1, 2006

### wakejosh

60kg * 9.8 m/s/s = 588 N
ok so 588 N * 4 m = 5352 J

2352/6 s = 392 Watts

pretty sure thats it. am i right?

5. Nov 1, 2006

### radou

You're right, except for mixing up the numbers. 588*4 = 2352.

6. Nov 1, 2006

### wakejosh

yea.. that was a typo. thanks.

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