Momentum

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MomentumImpulse
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• What does it mean to say roll with the punches?
• Why is it important to wear a helmet?
• Is it a good thing that cars basically crumble in
  an accident?

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Momentum

• What is momentum?

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• Can these two things have the same momentum?

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• Which of these will have the greater inertia?
  How do you know?

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• How can

have the same momentum as
?
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• The little girl can have the same momentum as the
  elephant if, when they are moving, her velocity
  is much greater than that of the elephant.

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Momentum isInertia in motion or mass in motion

• Momentum (p) is the mass of an object multiplied
  by its velocity
• p mv
• Units
• Momentum is measured in kgm/s

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Impulse

• What is impulse?

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• The Egg Test!

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Impulse

• Impulse is a change in momentum. It occurs when
  a force is exerted on an object over a certain
  amount of time
• Impulse (J) force times time
• J F x t

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Can we prove that

• Ft ?mv

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• The rubber ball paradox

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Elastic and Inelastic

• What does it mean to be Elastic?
• What does it mean to be Inelastic

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Elastic vs Inelastic Collisions
Elastic Collision When an object collides with
another object and returns back to its original
form. -a collision when a object bounces off
another object (they dont stick together)
Inelastic Collision When an object collides
with another object and does not return to its
original form. -when two objects stick together
(dont bounce off each other)
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Conservation of Momentum

• What does it mean to say the word
• CONSERVE

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Conservation of Momentum

• All momentum is conserved before an event and
  after an event.
• In other words. No momentum is ever lost. What
  we start with is what we end with. The TOTAL
  momentum never changes.

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Conservation of Momentum Problem
A 7000kg truck moving with a velocity of 8m/s
runs into and sticks to the back of a parked car
that has a mass of 2000kg. What is the velocity
of the combined cars after they collide?
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An Ice Hockey puck with mass 2kg is moving with a
velocity of 3m/s. It then collides with a
stationary rok that has a mass of .5 kg. If the
rok bounces off the puck with a velocity of 4m/s,
how fast is the puck moving?