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

Andrax · May 30, 2014

we have an inversed pendulum(ignore the car)

Diagram of an inverted pendulum on a cart: a point mass m at the end of a rod of length l, tilted at angle θ(t) from the vertical dashed line above the pivot. The cart has mass M, wheels, a horizontal position coordinate y(t) to the left, and an applied force f(t) pointing right.

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 · May 30, 2014

Where is the textbook putting the zero of h?

Andrax · May 30, 2014

ModusPwnd said:

Where is the textbook putting the zero of h?

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

Andrax · May 30, 2014

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

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

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