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? 


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? 


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? 







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.
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. 