(5)++Linear+Momentum

PAGE EDITOR(S): PaulaSuzanne Lapciuc, Eugenia Custo-Greig, Robert Figeroa-Downing, Luis de Armas

**Natland Note (11/30/09):** Animations look good, but need a little more of a description going along with them. In the car hitting the wall/bush, for example: what is this showing? Rather than just mentioning that it is like the egg example, what is this particularly showing? Additionally, remember that whenever you include a video or picture, have a caption beneath it describing why you put it on this page and how it ties into the content we discussed - what is the image/video showing or demonstrating? Also, remember links to other websites, etc.

The following file contains all the class notes on momentum:

This animation presents the same concept as the idea of an egg crashing against a pillow vs. a countertop. In this example the egg is the car, the pillow are the bushes and the countertop is the wall.

**Wall: D p = F D t** / **Bush: D p = F D t** The car comes to rest faster (over a shorter time interval) when it crashes into the brick wall, so more force is exerted onto the car than when the car crashes into the bushes, coming to rest over a longer time interval. When the car hits the wall, the force it experiences is greater because the Dp is the same for both but the collision with the wall happens in a smaller time interval which means the force it experiences is different.

Simple Momentum Problems:



An Animation on Momentum Conservation: T The animation below portrays the collision between a 1.0-kg cart and a 2-kg dropped brick. It will be assumed that there are no net external forces acting upon the two objects involved in the collision. The only net force acting upon the two objects (the cart and the dropped brick) are internal forces - the force of friction between the cart and the dropped brick. The before- and after-collision velocities and momentum are shown in the data tables. In the collision between the cart and the dropped brick, total system momentum is conserved. Before the collision, the momentum of the cart is 60 kg*cm/s and the momentum of the dropped brick is 0 kg*cm/s; the total system momentum is 60 kg*cm/s. After the collision, the momentum of the cart is 20.0 kg*cm/s and the momentum of the dropped brick is 40.0 kg*cm/s; the total system momentum is 60 kg*cm/s. The momentum of the cart-dropped brick system is conserved. The momentum lost by the cart (40 kg*cm/s) is gained by the dropped brick.

 For more in depth problems including more types of collisions and problems with both energy and momentum, plus another explanation on momentum visit: http://www.physics247.com/physics-help/momentum.shtm or __**http://www.physicsclassroom.com/Class/momentum/**__

Newton's Cradle is an example of momentum conservation. If no external force is applied to the system, then the sum of the momenta of those objects must remain constant. When the ball on th end hits the row of balls, the ball on the other end must react ot conserve the momentum.

media type="youtube" key="NS6aMdskKSo" height="344" width="425"

This one-inch punch works, in Bruce Lee's case, because he is exerting a great amount of force on a short time interval, making the impact greater.





Links: http://pdukes.phys.utb.edu/PhysApplets/collisions/Collisions.html (This link leads to an activity where you can change the masses and velocities of two blocks and see how it relates to each one's final velocity.)

http://www.animations.physics.unsw.edu.au/jw/momentum.html (This link leads to a page with many examples and short videos on momentum and collisions.)

Momentum Problems:

1) [] (A whole bunch of momentum problems)

2) http://id.mind.net/~zona/mstm/physics/mechanics/momentum/momentum.html ( simple momentum problems)

3) http://physics.bgsu.edu/~stoner/p201/momentum/ ( this site walks you through physics problems regarding momentum and collisions)

4)http://www.physicsclassroom.com/class/momentum/U4l2d.cfm (Physics Classroom guides you through the concepts and some examples)

1) Popular science article on a pretty awesome trick. media type="youtube" key="oxv61vgRRw8" height="344" width="425" Here's the article explaining the trick in terms of momentum: []=

media type="youtube" key="rGJ0fJN10YY" height="344" width="425" What happens when an object with high momentum hits another object? Flying Deer.

media type="youtube" key="JEmklTvAkbM" height="344" width="425" Example of a completely inelastic collision. Friction between his feet is why he doesn't move backwards.

Simple Momentum Problems: http://newton.burney.ws/physics/problems/momentum.php Animation for Momentum Conservation + Explanation: http://www.physicsclassroom.com/Class/momentum/ Newton's Cradle Animation: __**
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