Momentum = Mass x Velocity
"Momentum: What you give a person when
they are going away."
A boy in a 500kg car tosses a 2kg ball into the
air. The car is traveling at 4 m/s. What is the
momentum of the ball in the horizontal direction? 
[car] 


Momentum = 
mass
x velocity 


= 
2
kg x 4 m/s 


= 
8 kg
m/s 

What is the momentum of the 500kg car as it travels at 4 m/s? 
[car] 


Momentum = 
mass
x velocity 


= 
500
kg x 4 m/s 


= 
2000 kg
m/s 





A 30kg girl pushes against a 40kg boy when they are both
on ice skates. The girl shoots away at 4
m/second. How fast will the boy shoot away in the other
direction? 
[2 ice skaters] 






Girl’s
Momentum 
Boy’s Momentum 


mass
x velocity = 
mass
x velocity 


30 kg x 4
m/s = 
40
kg x V 


120 = 
40V 


Velocity = 
3 m/s 

Law of Conservation
of Momentum = "In
a system consisting of bodies on which no outside forces are acting; the total
momentum of the system remains the same."
Momentum
can be transferred from one object to another.
In an
interaction, the momentum lost by one mass equals the momentum gained by the
other.
Total
Momentum before interaction = The Total Momentum after.
[rolling a ball down a ramp]
What is the difference between inertia and momentum? 

Inertia is proportional
to mass. Large masses have more inertia than smaller masses. 
Momentum = mass x velocity 
Inertia is a property of mass and cannot change. Momentum
changes as an object changes its velocity. 