1. Momentum and Collisions http://www.youtube.com/watch?v=4ZrXUc6SA7c http://www.youtube.com/watch?v=4ZrXUc6SA7c

2. More ► http://www.youtube.com/watch?v=WxWHm 8V4lZo&feature=related Apophis in 2029 or 2036. http://www.youtube.com/watch?v=WxWHm 8V4lZo&feature=related http://www.youtube.com/watch?v=WxWHm 8V4lZo&feature=related

3. Linear Momentum ► Linear Momentum is a object with m and v. ► Symbol for momentum is p. ► Momentum is a vector. With direction that of velocity. ► Dimensions of p are m and v. ► SI units of p are what? ► What are some examples of p?

4. More Linear Mom ► What has more p an object with a large m or one with a smaller mass? ► What has more p an small object with a large v or a large object with a small v? ► What are some recent examples of an object with a large v and small m? ► Equation for p = mv.

5. Change in Momentum ► A change in p requires a F during a change in t. ► Ft = p Ft = mvf – mvi. Impulse p theorem ► Equations states that a small force over a long t period produces the same change in p as a large force acting during a short time. ► Follow through Greater change in p if object in contact for a longer period of t. ► http://www.physicsclassroom.com/curriculu m/momentum/mom1.pdf http://www.physicsclassroom.com/curriculu m/momentum/mom1.pdf http://www.physicsclassroom.com/curriculu m/momentum/mom1.pdf

6. Stopping times and distance ► Depend on I=p theorem.

8. Conservation of Momentum ► Momentum is conserved. ► http://www.physicsclassroom.com/mmedia/ momentum/index.cfm physics classroom http://www.physicsclassroom.com/mmedia/ momentum/index.cfm http://www.physicsclassroom.com/mmedia/ momentum/index.cfm ► http://www.bing.com/videos/search?q=car +airbag+collisions&view=detail&mid=62465 5912362DA14613B624655912362DA14613B &first=0&FORM=LKVR16 Car seat http://www.bing.com/videos/search?q=car +airbag+collisions&view=detail&mid=62465 5912362DA14613B624655912362DA14613B &first=0&FORM=LKVR16 http://www.bing.com/videos/search?q=car +airbag+collisions&view=detail&mid=62465 5912362DA14613B624655912362DA14613B &first=0&FORM=LKVR16

9. Conservation of Momentum Continued ► Mom + Mom = Mom + Mom ► MV1 + MV2 = MV1 + MV2 ► Before Col = After Col ► Two types of Collisions. Inelastic and Elastic. ► Regardless Momentum is conserved.

10. Collisions Conservation of Momentum ► Forces in real world situations are not constant. Always changing. ► Total p remains constant in any type of collision. ► Total KE is not always conserved because some is lost due to deformation of the object, heat, sound.

11. Perfectly inelastic collisions ► When two objects collide and move as one ► m1v1 + m2v2 = m1v1 + m2v2 ► m1v1 + m2v2 = (m1 + m2)v

12. KE not constant in inelastic collisions ► Total KE not constant when objects collide and stick together. ► The reason is that in inelastic collisions objects do not keep there shape. They deform.

13. Elastic Collisions ► Two objects collide and maintain or return to their original shape. ► They do not stick together. ► Most collisions are not truly elastic or perfectly inelastic. Because energy is lost. ► KE is conserved in elastic collisions.

14. Equation for elastic ► m1v1 + m2v2 = m1v1 + m2v2 ► KE equation ► ½ m1v1^2 + 1/2m2v2^2 = 1/2m1v1^2 + 1/2m2v2^2 ► Table 6-2

15. Collision lab ► Phet Lab Colorado: Collisions in one dimension. ► ► http://phet.colorado.edu/sims/collision- lab/collision-lab_en.html http://phet.colorado.edu/sims/collision- lab/collision-lab_en.html ► ► Lab one ► ► Lab two