# Homework Help: Power problem - finding altitude change

1. Nov 4, 2008

### apang42

1. The problem statement, all variables and given/known data

An electric scooter has a battery capable of supplying 140 Wh of energy. If friction forces and other losses account for 60.0% of the energy usage, what altitude change can a rider achieve when driving in hilly terrain, if the rider and scooter have a combined weight of 860 N?

2. Relevant equations

Ubattery= 140(.6)/3600s = .015556W
Ug= mgh

3. The attempt at a solution

.015556 = 860h
h = 1.8E-5
this is incorrect.

can anyone point me in the right direction? thanks for your help!

2. Nov 4, 2008

### heth

Units: What is the definition of a Wh?

3. Nov 4, 2008

### apang42

Wh = watt hours

4. Nov 4, 2008

### heth

But what does "Watt hours" mean? What does "140 Watt hours" mean? Can you explain that in words? It will help you with the problem. (If you're not sure, search for the definition of a kWh, a kilowatt hour.)

5. Nov 4, 2008

### csg39

you can get J out of it right? Then since you have J there is some equation to get m. maybe mgh? I don't know I need help on this problem too.

Thanks,
C

6. Nov 5, 2008

### heth

csg39 - in reply to your private message, please post the problem in the forum, including your attempts at a solution so far, where everyone can see and help.

7. Nov 5, 2008

### csg39

its the same problem as above.

8. Nov 5, 2008

### csg39

so i solved for velocity by using P=Fv=(mg)v

9. Nov 6, 2008

### heth

You'd need to explain how you did that - what you wrote down and what your thought process was - for people to be able to help you on here.

My other tip, if you're still stuck, would be to have a go at answering the question in post 4 of this thread.

10. Nov 6, 2008

### rsfactor

Hw can U equate power with mgh i.e energy?????????