# A rock weighing 98 newtons is pushed off the edge of a bridge 50 meters above the ground. What was the potential energy of the rock before it began to fall?

##### 1 Answer
Jan 6, 2017

$4900 J$

#### Explanation:

Gravitational potential energy is always measured relative to an origin. So in this case if ground level is taken as $G P E = 0 J$

the GPE of the rock is calculated by the formula

$G P R = m g h$

$m g \text{ }$ is the wieght

so $G P E = 98 \times 50 = 4900 J$