Interactive Rocketry Tutorial

NEWTON'S LAWS OF MOTION

All rockets make use of Newton's 3 Laws of Motion. Developed by Sir Isaac Newton in the 17th century. These 3 laws help to explain how and why a rocket can reach space. Sir Isaac Newton was one of the greatest scientists ever, and showed how many things that happen where things move, can be explained by simple laws.

Newton's 3 Laws are as follows:

1) Force is needed to change the Velocity of a body.

In the case of a rocket, the thrust of the rocket engines provides the force. This changes the velocity of the rocket, causing the rocket to accelerate upwards into space. When you see the Space Shuttle going faster, and faster, it is making use of Newton’s 1st Law.

2) The rate of change of Momentum of a body is equal to the resultant Force acting upon it. It takes place in the direction in which the force is applied.

This Law gives a very important physics equation called:

or, Force = mass x acceleration

where:

• F = the applied Force
• m = the mass of the body on which the force is acting
• a = the acceleration, or rate of change of velocity

The force is measured in Newtons.

This law explains why, if the Force is not large enough, it will never overcome the gravity pulling it back down, and will never leave the ground.

3) For every action, there is an equal and opposite reaction.

This law is what we see when the gas blasts out of the bottom of the rocket. The action of the rocket’s gas moving downwards causes a reaction, with the rocket moving upwards.

This page is maintained by Richard Osborne