### What makes a successful rocket launch?

Determining mass ratio is used on a large scale by aerospace engineers. There are many different things that determine whether or not a rocket will be able to efficiently lift off and mass ratio is one of them. Similar to how chemists calculate mass ratio by comparing the amounts of two chemical compounds, aerospace engineers calculate a rocket’s mass ratio by comparing the amounts of wet mass to dry mass. The wet mass is the rocket plus its fuel whereas the dry mass is only the rocket, so the less fuel needed to power the rocket, the smaller the wet mass and the whole mass ratio. An efficient rocket design will have low wet mass ratio and therefore a small mass ratio.

#### Creative Applications

- Guesstimate what the mass ratio of the space shuttle was.
- Will the mass ratio of a rocket going into orbit be greater or less than the mass ratio of a rocket traveling to the moon?
- True or False. The mass ratio must always be greater than 1.

#### Resources:

http://en.wikipedia.org/wiki/Mass_ratio