Download Momentum

Newton’s Third Law and
Momentum
Newton’s Third Law
 For every action there is an equal and opposite reaction.
 That means if I push on the wall the wall pushes back on me with the
same amount of force.
What is Momentum
 Momentum is how hard something is too stop.
 An objects mass and it’s velocity determine it’s
momentum.
Momentum
 The larger and objects mass the harder it is to slow down.
 The faster and object goes the harder it is to slow down.
Momentum
 The formula to calculate momentum is:
 Mass x Velocity
Momentum is represented by a symbol: p
The unites for momentum are: kg x (m/s)
Conserving Momentum
 Momentum can be transferred from one object to another.
 In fact momentum is always conserved.
 This is called:
The Law of Conservation of Momentum.
Conserving Momentum
 To conserve momentum one object smacks another object
and part of the force is applied to the second object.
 For this to happen it must be in a closed system.
 Closed system means no other forces are involved.
Example
A train car is sitting on the tracks, another train
car comes rolling up behind it and smacks in to the
first.
 What happens?
 The second car goes flying with the same
momentum as the first and the first stops.
Calculating Momentum
 If a bullet has a mass of 10 g and is traveling at 5
m/s what is the momentum?
 p = mass x velocity
p = 10 x 5
p = 50 g(m/s)