# What is the gravitational potential energy of a  9 kg object on a shelf  2/3 m  high?

Apr 18, 2016

$P {E}_{g} = 176 J$

#### Explanation:

Gravitational potential energy is proportional to the mass of an object (the more mass the more energy), and the height above some reference point (the higher the object the more energy), where the constant of proportionality is $g$ - the acceleration due to gravity. This can be written as the equation:

$P {E}_{g} = m \cdot g \cdot h$

where $g = 9.8 m / {s}^{s}$ on Earth. Plugging in the values from the question we get

$P {E}_{g} = 9 k g \cdot 9.8 m / {s}^{2} \cdot \frac{2}{3} m = 176 k g \cdot {m}^{2} / {s}^{2} = 176 J$