Transcript Physics 1-3-08 - elyceum

Physics 1-3-08
Introduction of momentum
What will be done the next two
weeks
• We will be discussing the concept of
Momentum until Wednesday of next week
• Next Thursday/Friday will be spent on
review for test
• Find your old tests, use as a basis for
studying.
New Year New Books (almost)
• We have new books, but are one short
• If somebody is absent, or If I have 2 that
really want to share
• Have asked for another book…
Those getting books
• Enter book #, (if it has not already been
done)
• Write name and year in front
• Sign list, for teacher
Question
• What would you rather get hit with?
• A bowling Ball or a steel ball bearing?
On what does your answer
Depend?
Momentum
• Multiply the two factors together and you
can begin to quantify the risk in being hit
by the object
• The name of the value is called
momentum
Momentum
• “Pain upon impact”
• “Inertia in motion”
• Quantity of motion found by multiplying an
objects mass by its velocity
• It is a vector value (Magnitude and
Direction)
• Units Kg m/s
What does not have momentum?
What has more momentum?
• The statue of liberty or a SUV moving at
60 mph done the road?
How can one change momentum?
• Examples of objects changing their
momentum
Impulse
• The measure of a change in momentum
• Any change in momentum requires a net
force
• Any application of a net force, results in a
change of momentum of the object
What is Newton’s second law?
To find the impulse of an object
• Fnet Δt = m Δ v = impulse
Car Crashes
• Why do some people survive and others
do not?
Important
• For a given crash, the impulse is
constant regardless of how the crash
occurs
• Impulse = mΔv
Time and force
• The length of time it takes for the crash to
be complete determines the amount of
force applied during the crash
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Seat belts
Foam padding
Air Bags
Crumple zones
Change of momentum and Sports
• Baseball/ softball
•
Golf
Homework
• New Book!
• Page 233
• Problems 1-5