How Rockets Work

With a little history thrown in for fun

Hero Engine

~100 BC

Chinese Rockets - “Fire Arrows”~1200 ADin Military Use

First Manned Rocket?

Isaac Newton

• 1687• Laws of Motion• Paved way for

modern rocketry

Robert Goddard

First Liquid Fueled Rocket

German Scientists Develop Long Range Missiles during World War II

Newton’s Laws of Motion

• In the absence of net external force, objects tend to maintain their state of motion

• Acceleration is directly proportional to force applied and inversely proportional to mass

• For every action force, there is an equal but opposite reaction force

In the absence of net external force, objects tend to maintain their state of

motion

• If nothing pushes or pulls– Objects at rest, stay at rest– Objects in motion move in a straight line with

constant speed

Acceleration is directly proportional to force applied and inversely proportional to

mass• If you push harder– The motion changes faster

• If the object is heavier– You must push harder to get the same change in

motion

For every action force, there is an equal but opposite reaction force

• Forces come in pairs• When an object can’t push back any harder, it

moves away to lessen the push it is getting

He pushes the rock The rock pushes back

Applied to Rockets• The rocket will stay where it

is until the engines ignite. The rocket will keep moving when the engines stop.

• More mass requires bigger engines

• Gasses are pushed backward by the rocket (action) the rocket is pushed forward by the gasses (reaction)