Newton's Laws

Newton’s 1st law

The velocity of an object will not change unless a resultant force acts on it

If forces aren’t balanced on an object, what happens

The object accelerates

Newton’s 2nd law

Acceleration is proportional to the force

Newton’s Second Law equation

ΣF = ma

What happens if you apply more force to an object

It will accelerate more

For a given force, increasing mass means what

Less acceleration

What does ΣF mean

Vector sum of all forces (resultant force)

Which direction does acceleration due to Newton’s second law occur

In the same direction as the resultant force

Explain how Newton’s 1st and 2nd Law are related

When ΣF=0, for any object with a mass acceleration must = 0, so an object with no resultant force will have a constant velocity

Galileo’s law of falling bodies

All objects fall at the same rate if you ignore air resistance

Ignoring air resistance, explain which object falls faster- a heavy ball, or a light ball

Neither- weight (W=mg) is the only force acting on the balls, so for each mg = ma

The m cancels out, so a = g for both balls so a = a

Newton’s 3rd Law

If an object A exerts a force on object B, then object B exerts an equal but opposite force on object A