Page 50 - @ccess 2 Reader´s Book

Why Does a Rocket Work?

In the vacuum of space, an engine has nothing
to push against. So how do rockets move there?
Rockets work by a scientific rule called Newton's
third law of motion.

English scientist Sir Isaac Newton listed three Laws
of Motion more than 300 years ago. The third law
says that for every action, there is an equal and
opposite reaction.

When the rocket pushes out its exhaust, the exhaust
also pushes the rocket. The rocket pushes the
exhaust backward. The exhaust makes the rocket
move forward. This rule can be seen on Earth. If
a person stands on a skateboard and throws a
bowling ball, the person and the ball will move in
opposite directions. Because the person is heavier,
the bowling ball will move farther.

When Were Rockets Invented?

The first known rockets were used in China
in the 1200s. These solid rockets were used
for fireworks.

They also were used by armies for war. In
the 1300s, these rockets were used for the same
purposes through much of Asia and Europe. In
the next 600 years, people developed bigger
and better solid rockets. Many of these were used
by the military.

Reader's Book 49