rush out the end, the rocket moves in the opposite direction, as predicted by Newton’s Third
Law of Motion. The reaction force of the gases on the rocket pushes the rocket forward, as
shown inFigure23.17. The force pushing the rocket is also calledthrust.
Figure 23.17: Explosions in a chamber create pressure that pushes gases out of a rocket.
This in turn produces thrust that pushes the rocket forward. The rocket shown here is a
Saturn V rocket, used for the Apollo 11 mission––the first to carry humans to the Moon. ( 4 )
A Rocket Revolution
For centuries, rockets were powered by gunpowder or other solid fuels. These rockets could
travel only fairly short distances. At the end of the 19thcentury and the beginning of the
20 thcentury, several breakthroughs in rocketry would lead to rockets that were powerful
enough to carry rockets—and humans—beyond Earth. During this period, three people
independently came up with similar ideas for improving rocket design.