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I was doing my Physics homework without my school notes, and then I stumbled on a problem involving potential energy.

The equation for potential energy, as I have found out, is PE = mgh where m is the mass in kilograms, g is the gravitational acceleration (9.8 m/s^2) and h is the height of the object in question.

The problem, however, does not give me the mass of the object:

"What is the potential energy of a 250 N [Newton] bike that is on top of a 5 meter ramp?"

So Newtons are measures of force... But only one of the variables is given: h, or the height.

I suspect that there is an alternative equation for potential energy, which is likely because I don't have my notes. A Google search has only yielded the formula I already have.

Any thoughts? Thank you.

You can calculate the mass of the bike using the 250 N.
F = m / a ( F being the Force = Newton )
rearrange that to
m = F / a

It's a pretty heavy bike though. Hope this is correct.

(11-01-2009, 02:27 PM)TheDoctor Wrote: [ -> ]You can calculate the mass of the bike using the 250 N.
F = m / a ( F being the Force = Newton )
rearrange that to
m = F / a

It's a pretty heavy bike though. Hope this is correct.

Thanks, I think I'm getting on the right track.

But I thought the formula was F = m*a

(11-01-2009, 02:31 PM)Korchidoom Wrote: [ -> ]Thanks, I think I'm getting on the right track.

But I thought the formula was F = m*a

wooops sry. It is. Damn typo.

Alright, so M = f / a.

For the acceleration, would I substitute in 9.8 m/s^2?

(11-01-2009, 02:42 PM)Korchidoom Wrote: [ -> ]Alright, so M = f / a.

For the acceleration, would I substitute in 9.8 m/s^2?

Yup.

Thank you very much. You will be +repped as soon as I get 100 posts.