Newton’s Three Laws of Motion

In I/GCSE Physics,

**First Law**: **Balanced Forces means there will be** **No change in Velocity**.

- Balanced Forces are when the forces Resultant Force is equal to zero. e.g.
**xN – xN = 0N**. - According to the First Law of Motion this statement
**must always be true**.

**Second Law:** **A Resultant Force Means there will be** **Acceleration**.

- The object on which a
**Resultant Force**is acting upon will always**Accelerate**according to Newton’s Second Law. - Basically, if you push something, it will
**move**and thus Accelerate.

**Third Law: If object A exerts a Force on object B then object B will exert an equal opposing Force on object A.**

- Essentially, what it means is that if you push something like a toy car, then that toy car is going to
**push back against**you with**equal Force**. This is called a**Reaction Force**.

So, what does **General Force** mean in I/GCSE Physics?

The formula for General Force (as in the force that occurs from the **kinetic energy** of more conceivable Force, like pushing a door shut) is extremely useful. With it, we can calculate, and thus predict, things like how much **Force** will be exerted upon the car in a car crash, saving countless lives. The formula is **F = ma (Force = Mass × Acceleration)**

**Example**

A car has lost control of its breaks and is heading for a concrete wall. Its **Mass is 2000kg**

and it is **Accelerating at 20m/s**. With what amount of force will the car hit the wall?

**F = ma**, therefore we simply sub in our values for **Mass and Acceleration** into the formula. Tremendously easy! **20 × 2000 = 40000N** *(this is an extremely large Force and 20m/s Acceleration is an insanely fast rate at which to Accelerate)*

Challenges:

Another car comes speeding, crashing into the back of the first car. The car crashes with

a **Force of 28000N** and it’s mass was **300kg**. What was the car’s Acceleration?

**Formula for Force: F = ma (Force = Mass × Acceleration)**

End of this topic!