Momentum and Newton's laws of motion (3.1)

What is mass? and what is its relation to motion?

Mass - the amount of matter in an object

Thus mass is a property of an object that resists change in motion

What is weight? and how does it differ to mass?

Weight - the effect of a gravitational field on mass

W=mg

Where W is in N

m is in Kg

g is in ms^-2

Weight vs Mass

Weight can differ depending on the gravitational pull whereas mass is constant. E.g. on the moon someone will have a lower weight but the same mass

What is Newton’s first law?

1^st law - a body will remain at rest or move with constant velocity if no resultant force acts on it

What is Newton’s second law?

2^nd law - the acceleration of a body of constant mass is proportional to the resultant force applied to it and in the direction of the resultant force

2^nd law - the rate of change in momentum is proportional to the magnitude of the force

F_NET = ma

Where F_NET is in N

Where m is in Kg

Where a is in ms^-2

What is Newton’s third law?

3^rd law - when an object exerts a force on another object, the other object exerts a force of equal magnitude in the opposite direction / whenever two bodies interact, the forces they exert on each other are equal and opposite

Forces always occur in pairs

The force pairs must be:

• The same type of force

• The same magnitude

• Opposite in direction

• Acting on different objects

Linear momentum