Physics 101
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Transcript of Physics 101
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Physics 101
General Physics
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Who am I?Dr. BrutonI may be teaching the remainder of
this course for Mr. Carlton.We have similar teaching styles.There will be extra credit.I will “teach to” Mr. Carlton’s test.I will hit the highlights of the chapters
with PowerPoint presentations.
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Let’s take notes…
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Chapter 6Chapter 6
MomentumMomentum
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Momentum and CollisionsMomentum and Collisions
This chapter is concerned with inertia and motion.
Momentum helps us understand collisions.
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Momentum and CollisionsMomentum and Collisions Elastic Collisions– objects rebound– e.g. superball
Inelastic Collisions– object stick together an usually
become distorted and generate heat– e.g. clay ball
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Momentum
Momentum = mass velocity
p = mv
Momentum is a vector quantity.
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A large truck has more momentum than a car moving at the same speed because it has a greater mass.
Which is more difficult to slow down? The car or the large truck?
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Large Momentum Examples:
– Huge ship moving at a small velocity
– High velocity bullet
P = mv
P = mv
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Impulse
In order to change the momentum of an object you must apply a force over some time interval.
Impulse = Force time interval = F t
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Impulse and Momentum
Impulse = Change in Momentum = Final (mv) - Initial (mv)
F t = (mv)
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Case 1: Increasing Momentum– Apply a force for a long time. – Examples: • Follow through on a golf swing.• Pushing a car.
Ft
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Case 2: Decreasing Momentum – Apply a force for a long time.– Examples:• Air bags in cars. • Catching an egg.• Boxing, Figure 6.6• Soft collisions, Figure 6.3.
Ft
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Case 3: Decreasing Momentum– Apply a force for a short time.– Examples: • Boxing• Karate
Ft
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Conservation of MomentumThis means that the momentum doesn’t
change.
Recall that F t = mv)
In this equation, F is the "external force".
Internal forces cannot cause a change in momentum.
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ExamplesConservation of Momentum: If
there are no external forces, the total momentum for a system remains unchanged.
Example 1: a person sitting inside a car pushing against the dashboard
Example 2: a bullet fired from a rifleExample 3: a rocket is space
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Example Problems...