Why is potential energy considered negative in an inversed pendulum system?

[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 textbook they basically take the absolute value of h i don't understand why?

 

[ModusPwnd]

Where is the textbook putting the zero of h?

 

[Andrax]

Where is the textbook putting the zero of h?

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

 

[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