Lesson Strategy- Impulse and Momentum
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Transcript of Lesson Strategy- Impulse and Momentum
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7/27/2019 Lesson Strategy- Impulse and Momentum
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Review that:
Bodies at rest will remain at rest
while bodies in motion will
continue to move at a constantvelocity unless a net force is
acted upon them(First Law: Law of Inertia)
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Review that:
Inertia is the tendency of the
body to retain its state of motion
(either at rest or in motion)
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Review that:
Mass is the quantitative measure
of the objects inertia. The
greater is its mass, the greater isits inertia.
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Review that:
The acceleration of an object is
directly proportional to the Net
Force applied on it and inverselyproportional to its mass
(Second Law: Law of Acceleration)
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Review that:
Acceleration is the objects
change in velocity over a certain
period of time
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Case 1:
Two balls (tennis and bowling balls)
are rolling with the same velocity on
a smooth floor. Which between themis much easier to stop?
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Time = 0 seconds
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2 seconds later
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Case 2
A soccer ball which is initially at
rest experiences a change in
velocity to 5m/s
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How would you describe the
motion of the ball?
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What would have caused the ball
to accelerate?
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How quick are your eyes? Identify velocity, force, mass and time.
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Its time to share
what you observed!
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Analyze and solve:
A 25,000 kg bus from Tuguegarao
moves at 25 m/s to Ilagan. What
is the momentum of the bus?Assume that the velocity of the
bus is constant.
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Analyze and solve:
John hits a 0.05 kg ball, going at a
speed of 65m/s. What is the
impulse to the ball?
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Analyze and solve:
Automobile companies often test the
safety of cars by putting them through
crash tests to observe the safety of thepassenger compartment. If an 1100 kg
car is sent towards a cement wall with a
speed of 15 m/s and the impact stops thecar in 0.09s, with what average force is it
brought to a stop?
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Associate yourmathematical
relationship
Ft = mvwith this:
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Associate your mathematical relationship Ft = mv
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Associate your mathematical relationship
Ft = mv
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Catching Raw Eggs
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Apply what you learned:
If you are catching a fast baseball
with your bare hand, you extend
your hand forward so youll haveplenty of room to let your hand
move backward, extending the time
of impact and thus reducing theforce of impact.
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Apply what you learned:
A person jumping from an elevated
position bends his knees upon
making contact (thereby extendingthe time during which his
momentum is being reduced by 10
to 20 times that of a stiff-leggedabrupt landing.
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Test your understanding:
Interpret the situation
illustrated on the next
slide!
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Question 1:
If the boxer is able to make the
duration of impact three times as
long by riding with the punch, byhow much will the force of
impact be reduced?
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Question 2:
If the boxer instead moves into
the punch as to decrease the
duration of impact by half, byhow much will the force of
impact be increased?
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Assignment:
Follow-up assignment:
Explain how the concept of impulse and
momentum is applied when the karate expert
fracture a stack of bricks with the blow of his barehands.
Advanced assignment:
How is momentum conserved?
Differentiate elastic from inelastic collision.
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Picture credit to Jericho Torres, IV-Alpha 2010-11.
Domo arigatou
gozaimasu!Thank you very much!