MYIB / Honors Physics

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Impulse and Momentum

• MYIB / Honors Physics

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Using Physics terms, what put the egg in motion?
Once the egg was moving, why did it keep moving?
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Momentum equals mass times velocity.
Unit
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Using Physics terms, how did you stop the egg?
Then if you multiply both sides by
t, then
Notice the right side of the equation, What
physics term is defined by that part of the
equation?
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The quantity Ft is called an Impulse.Impulse
Change in Momentum

• Units of Impulse
• Units of Momentum

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Example

• A 5.00 kg mass initially at rest is acted on by a
  horizontal force of 20.0 N for a time of 3.50 s.
• What is the change in momentum of the mass?
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• What is the speed of the mass at the end of the
  3.50 s?
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Example

• A 4.00 kg object moving at 5.00 m/s is acted on
  by an unknown force for 10 s until it reaches a
  speed of 15.0 m/s.
• What is the initial momentum of the object?
• b. What is the final momentum of the object?
• c. What is the change in momentum of the object?
• d. What is the magnitude of the force that acted
  on the object?
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Impulse is the Area

• Since JFt, Impulse is the AREA of a Force vs.
  Time graph.

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If the tennis ball is released at eye level and
allowed to fall freely due to the pull of
gravity, is it possible for the tennis ball
bounce higher than your head without placing
anything on the ground for the ball to bounce off?
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Momentum is conserved in the collision!

• The Law of Conservation of Momentum

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Several Types of collisions

• Sometimes objects stick together or blow apart.
  In this case, momentum is ALWAYS conserved.

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Example

• Granny (m80 kg) whizzes around the rink with a
  velocity of 6 m/s. She suddenly collides with
  Ambrose (m40 kg) who is at rest directly in her
  path. Rather than knock him over, she picks him
  up and continues in motion without "braking."
  Determine the velocity of Granny and Ambrose.

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Example
At an amusement park, a 96.0 kg bumper car (A)
moving right with a speed of 1.50 m/s bounces
elastically off a 135 kg bumper car (B) at rest.
After the collision, bumper car B moves right
with a speed of 0.8888 m/s. What is the speed and
direction of bumper car A after the collision?