Practice Lesson Plan

Momentum and Collision

Mr. SullivanPre-AP PhysicsGrades 10-12

Thursday, April 14, 2011

Today’s Objectives


Today’s ObjectivesUnderstand the ideas of (a) momentum, (b) conservation of momentum, and conversation of momentum in (c) elastic and inelastic collisions.



Interpret questions related to real life examples of (a) momentum, (b) conservation of momentum, (c) inelastic collisions, and elastic collisions.




Compose a logical procedure to solve for required information from prior questions.




Compose a logical procedure to solve for required information from prior questions.

Design and Reconstruct personal examples of momentum, conservation of momentum, inelastic collisions, and elastic collisions.


What is Momentum?


What is Momentum?Momentum is the vector quantity that represents a mass with a velocity at specific moment in time.



Or



Or

Momentum is mass in motion.


How do we represent momentum?

We represent momentum with the equation...

p = m x v

Where,

p = momentum (kg x m/s)

m = mass (kg)

and v = velocity (m/s)


What are some real world examples of

momentum?


Example problemWhat is the momentum of a 747 jet (400,000 kg)that is traveling south from Dallas to Houston at a

velocity of 900 km/h (250 m/s)?




First Define the variables and draw a diagram.




First Define the variables and draw a diagram.The Known or what values are given to us.




First Define the variables and draw a diagram.The Known or what values are given to us.The Unknown or what are we solving for.





Second Define the equation we need to use.





Second Define the equation we need to use.Third Plug in the known values and solve for the unknown.






Last does your answer make sense?


AnswerThe 747 jet has a momentum of

100,000,000 kg x m/s in the southern direction.


What is conservation of momentum?



The conservation of momentum is the fundamental law that objects acting in a closed

system will maintain momentum through collisions with other objects in the system.





Or





Or

When two objects collide the starting momentum of the objects will be the same as

the finishing momentum of the objects.


How do we represent conservation of momentum?

We represent conservation of momentum of two objects with the equation...

p1i + p2i = p1f + p2f

Where, p1i = the initial momentum of object 1p2i = the initial momentum of object 2p1f = the final momentum of object 1p2f = the final momentum of object 2The Equation can also be written as...

(m1 x v1i) +(m2 x v2i) = (m1 x v1f) + (m2 x v2f)Thursday, April 14, 2011

What is the difference between elastic and inelastic collisions?



An elastic collision is when objects collide and bounce apart.




Such as when a tennis ball hits a racket.





An inelastic collision is when objects collide they stick together.





An inelastic collision is when objects collide they stick together.

Such as when someone jumps into a boat sitting still.


What are some real world examples of conservation of

momentum?


Example ProblemAnn (65 kg) is roller skating west at 12 m/s, and hits Joe (49 kg) who is also on skates but who was standing still. Ann comes to complete stop after she hits Joe. What is Joe’s velocity after the collision?



First Define the variables and draw a diagram.



First Define the variables and draw a diagram.The Known or what values are given to us.




Second Define the equation we need to use.





Last does your answer make sense?


AnswerJoe will be rolling at 15.9 m/s west.


Same Question


Same QuestionExcept now Ann grabs on too Joe and they start rolling together. What is the resulting velocity

of the two roller skaters?




Answer




AnswerAnn and Joe are rolling at 6.8 m/s to the west.


Review


ReviewMomentum is mass in motion



p = m x v



p = m x vConservation of momentum means the starting momentum equals the

ending momentum.



p = m x vConservation of momentum means the starting momentum equals the

ending momentum. p1i + p2i = p1f + p2f

(m1 x v1i) +(m2 x v2i) = (m1 x v1f) + (m2 x v2f)


Review


ReviewAn elastic collision is when objects move

separately even after a collision


ReviewAn elastic collision is when objects move

separately even after a collision

An inelastic collision is when objects move together as one mass after a collision.


Furthering Your Understanding

You Tube Videos:

http://www.youtube.com/watch?v=eQ3RfKPPO2o

http://www.youtube.com/watch?v=UcFz1L4BFcA&feature=related

http://www.youtube.com/watch?v=mR8kDvCmHQA&feature=












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