Download Impulse and Momentum

Momentum and
Its
Conservation
Impulse and Momentum
• Objectives
– Compare the system before and after an
event in momentum problems
– Define the momentum of an object
– Determine the impulse given to an
object
– Recognize that impulse equals the
change in momentum of an object
Momentum
• What is momentum?
• The Seattle Seahawks had
momentum entering the final weeks
of the season…
• Anything that is moving
has momentum
• Depends on what?
Momentum
• Momentum = mass * velocity
• In physics, the symbol for momentum
is “p”
sssooo…
• p=m*v
• SI units are kg·m/s
Which has more momentum, a
supertanker tied to a dock or a raindrop
falling?
Momentum
• Determine the momentum of a ...
– 60-kg halfback moving eastward at 9
m/s.
• 60 x 9 = 540 kg·m/s east
– 1000-kg car moving northward at 20
m/s.
• 1000 x 20 = 20,000 kg·m/s
– 40-kg freshman moving southward at 2
m/s.
• 40 x 2 = 80 kg·m/s
Impulse and Momentum
• Impulse = Change in momentum
• Impulse
– The product of the average net force
exerted on an object and the time
interval over which the force acts
– N•s
Real Life Applications..
• Sports…
– Follow-through!
– Gymnastics Mats
• Cars…
– Airbags!
– Before airbags….
– Bumpers
• Eggs…
• Jumping…
– Knees
– Shoes
Review
• Can a bullet have the same
momentum as a truck?
The Conservation of
Momentum
• Objectives
– Recognize the conditions under which
the momentum of a system is
conserved
– Apply conservation of momentum to
explain the propulsion of rockets
– Solve conservation of momentum
problems in two dimensions by using
vector analysis
The Law of Conservation on
Momentum
• The total momentum of two objects
before a collision is equal to the total
momentum of the two objects after
the collision.
• P(before) = P(after)
Two Particle Collisions
– Inelastic collisions
mAvA1 + mB1vB1 = mAvA2 + mBvB2