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Momentum
SQ4R: Momentum
Lesson 1 from Momentum & Collision Chapter at the Physics Classroom
Survey (No writing)
Recite
• Check out headings, captions, & subtitles
• Summarize the reading in your own words
(2 sentences max for each section)
Question (What do you know about momentum?)
• What do you already know about this subject?
• Why is this being assigned by the teacher?
Read
• Ask 3 questions & write down unknown terms
• Reread passages that are unclear
• Relate back to your questions & teacher
questions after each passage
• Take quotes of important ideas or parts
Respond
• Fill in “Momentum, Impulse, & Momentum
Change” Worksheet.
Review
• Review your notes
• Answer any questions that may have been
resolved by reading
• Define unknown terms
Take notes for your SQ4R on a separate sheet and staple to your momentum and collision worksheet
Momentum-”mass in motion”
• All objects have mass, therefore if an object is in motion it has momentum.
• How much stuff is moving and how fast the stuff is moving
• Momentum is dependent on mass and velocity
• p=mxv
• Vector quantity
• Units kg*m/s direction
• Example: What is the momentum of a 200kg elephant charging east at
5m/s?
Momentum and Impulse
• Remember acceleration is the result of an unbalanced force
• Newtons 2nd Law
f= m x a or F = m x Δv/t
• Impulse is the change in momentum
• F x t = m x Δv , where F x t is the quantity impulse
• Impulse occurs whenever a force acts upon an object for a certain
amount of time resulting in a change in momentum.
• Impulse=Change in momentum
Impulse and Collision
• In a collision, an object experiences a force for a specific amount of
time, which results in a change in momentum. The mass either speeds up
or slows down.
• This means that during a collision an object experiences IMPULSE!
• Impulse experienced by an object in a collision is equivalent to a
change in momentum. F x t = Δp (units= N x s)
Impulse: Importance of Direction
• Momentum is a vector quantity
• The direction of impulse relative to the direction of momentum
must be taken into consideration.
• Impulse in the same direction results in an increase of momentum
equal to the amount of impulse.
• Impulse in the same direction results in an decrease of
momentum equal to the amount of impulse.
Rebounding Collision
• A collision involving a change in direction and speed is known
as a rebound collision
• Elastic collisions rebound with the same speed (large change in
velocity!)
Impulse-momentum Change Theorem
F x t = m x Δv
• Force and time are inversely related therefore as the time in which the
collision occurs increases the force decreases and vice versa.
• To minimize applied force collision time can be increased (Airbags-extend
the time required to stop the momentum of the driver)
• To maximize force collision time must be decreased (When is this a good
thing?)