Momentum = Mass x Velocity

"Momentum: What you give a person when they are going away."





A boy in a 500-kg car tosses a 2-kg 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 500-kg car as it travels at 4 m/s?




Momentum =

mass x velocity




500 kg   x  4 m/s




2000 kg m/s









A 30-kg girl pushes against a 40-kg 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 =




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.





 Rube Goldberg Machines



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