Transcript Momentum Notes

Momentum
“Why can you stop a baseball traveling
at 40 meters per second but not a car
traveling at 1 meter per second?”
Momentum defined
• Measure of force needed to stop a moving
object
– Objects MUST be moving to have momentum
• Formula:
– Momentum = mass x velocity
P  mv
p = momentum
m = mass
v = speed or velocity
Conservation of Momentum
• The total momentum of any group of
objects remains the same unless an
outside force acts on the objects.
– What “outside” forces?
• Friction
• Heat
• Energy transfer
– The momentum before a collision =
momentum after after a collision
Newton’s Cradle
Momentum of train cars
• “Why can you stop a baseball traveling at 40
meters per second but not a car traveling at
1 meter per second?”
– A baseball has a mass of 0.15 kilograms and the car has
a mass of 1500 kilograms. What is the momentum of
each object?
– Formula:
p=m∙v
– Substitutions:
p = 0.15kg ∙ 40 m/s
– Answer with units: p= 6.0 kg ∙m/s
– Formula:
p=m∙v
– Substitutions:
p = 1500kg ∙ 1m/s
– Answer with units: p= 1500 kg ∙m/s