Fact 1: An automobile engine transforms chemical energy into mechanical energy.

Fact 2: Rocket engines are reaction engines.

Given the two facts above, answer the question "What powers rockets?" with the following options: 
- supersonic
 - a hydraulic system
 - sun's heat
 - Mechanical energy
 - direct energy
 - fossil fuels
 - hydrogen and oxygen
 - electromagnetic energy


 

    Mechanical energy     