Potential Energy is Negative?

1. May 30, 2014

Andrax

we have an inversed pendulum(ignore the car)

and we choose the coordinate system to be upwards
the potential energy PE=mgz (z will be hegative since( O,k) is upwards right?) z is always under O.
but in the text book they basically take the absolute value of h i don't understand why?

Last edited: May 30, 2014
2. May 30, 2014

ModusPwnd

Where is the text book putting the zero of h?

3. May 30, 2014

Andrax

at the point of rest of the pendulum (same as O)

4. May 30, 2014

Andrax

fixed the problem (h ad to do with angle being negatgive which means the work of p is negative)
sorry my explication of the question was off , close this thread