Transcript Momentum and Impulse

Vocabulary Quiz-Friday
How difficult is it to get something to
change its momentum?
P=mv
What could be
manipulated in
order to change the
football player’s
momentum?
• Brick wall?
• Dinosaur eating
football player?
P=mv
A change in momentum would mean a
change in either the mass or velocity.
We’ll always assume the velocity changes.
What causes a change in velocity?
a Force
Impulse
also known as change in momentum
Impulse= (force)(time)
= FΔt
Unit is Newton-second
N-s
Increasing Momentum
Increasing Momentum
“Follow through” in sports
1) Apply the greatest force possible for the
longest time possible
Impulse= (force)(time)
= FΔt
Decreasing Momentum
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Decreasing Momentum
The change in
momentum may be
b/c of a small force
exerted over a long
time
The change in
momentum may be
b/c of a large force
exerted for a short
time
Decreasing Momentum
To minimize the effect
of the force on an
object involved in a
collision, the time
must be increased.
Other examples that decrease the
force by increasing the time
• Air bags
• Catching a baseball
with a glove
• Fighting with padded
gloves v. bare fists
• Rolling with a punch
Padded dashboards
• Packing materials
• Crumple zones
• New seat belts
Practical application
Observe that the
greater the time over
which the collision
occurs, the smaller
the force acting upon
the object.
Cradling the ball
 A water balloon is thrown high
into the air and successfully
caught. The key to the success
is to contact the balloon with
outstretched arms and carry the
balloon for a meter or more
before finally stopping its
momentum. The effect of this
strategy is to extend the time
over which the collision
occurred and so reduce the
force.
 This same strategy is used by
lacrosse players when catching
the ball. The ball is "cradled"
when caught;
Other examples where extending your
time decreases the force
• Bungee jumping
• Bending your knees when you jump, not
locking them
• Safety nets/ giant air mattresses (during
fires, circuses)
Impulse Activity
• Monday it is
supposed to be 80
degrees
• Good Luck!