# A student launches a 50 g marble vertically with an elastic band. If the marble reaches a height of 10 m, how much elastic potential energy did the student put into the elastic band?

Nov 26, 2015

$4.9 \text{J}$

#### Explanation:

Using the conservation of energy we can say that the elastic energy stored in the band will be converted in gravitational potential energy which we can get from:

$P E = \text{weight"xx"height}$

This becomes:

$P E = m g h$

$\therefore P E = 0.05 \times 9.8 \times 10 = 4.9 \text{J}$

So stored energy = $4.9 \text{J}$