What does it mean for PE to be dependent on the reference level?

The potential energy of an object is the energy possessed by the object due to its position in a gravitational field.

Mathematically, it is given by:

where

m is the mass of the object

g is the acceleration due to gravity at the location of the object

h is the height of the object

As we can see, the potential energy depends on the height of the object, h.

However, this height is relative, since it can be measured using different reference levels.

Generally, the reference level is taken to be the ground; so for example, an object located at the top of a cliff 40 m above the ground, has

h = 40 m

But this value is of course relative, since we can also take the reference level to be the top of the cliff, so in that case, we would have

h = 0

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.