Newton's first and third laws
Learn about Newton's first and third law.
This lesson includes:
- one video
- two activities
Sir Isaac Newton was a very intelligent man.
During the 17th Century, he developed three laws of motion that govern how all objects move.
In this lesson you will look at the first and third laws.
Newton's first law
According to Newton's First Law of motion, an object remains in the same state of motion unless a resultant force acts on it.
If the resultant force on an object is zero, this means:
- a stationary object stays stationary
- a moving object continues to move at the same speed and in the same direction
When a car travels at a constant speed, the driving force from the engine is balanced by resistive forces such as air resistance and friction in the car's moving parts.
The resultant force on the car is zero.
Newton's third law
Now watch this short film where Jon Chase explains Newton's third law of motion.
Newton's third law states:
For every action, there is an equal and opposite reaction.
This means, if you push on something (action) it pushes back (reaction).
On a racing car the wheel tries to push the road backwards (action) and in return the road pushes the wheel and the car forwards (reaction).
There are lots of ways to try out your science skills.