# LINEAR MOMENTUM AND COLLISIONS

1N10.20 EGG AND SHEET
1N22.20 WATER ROCKETS
1N30.10 COLLIDING BALLS
1N30.15 BILLIARD BALL COLLISION
1N30.17 MAGNETIC BALL COLLISION
1N30.50 ELASTIC VS INELASTIC COLLISIONS

 1N10.20 Egg And Sheet Toss egg into sheet held by students. Same idea as air bag: hard fast stop (large F) or soft slow stop (small F). Momentum change is same either way. Note that it is an egg toss not a baseball pitcher throw. See pictures at this web site of how to hold sheet: http://courses.ttu.edu/thomas/science-demos/egg%20toss/pics.htm. As an alternative have one student throw an egg and see if another student can catch the egg without breaking it. A second alternative is to drop an egg onto a thick foam pad after first dropping one on desk. Cover desk with newspaper first. Setup Requirements: At least 24 hr advance notice or bring your own eggs. Take towels to clean up mess if sheet missed.   Equations: F = dp/dt   Safety Issues: Being hit by egg

 1N22.20 Water Rockets Compare thrust of rockets filled with air and water with equal number of pumps. Setup Requirements: When ready to do fill rocket partly with water using yellow or orange cup. Attach pump. Use pump to increase air pressure. Pull trigger to fire.   Equations: Thrust = u x dm/dt   Safety Issues: Moving projectile,wet clothes

 1N30.10 Newton's Collision Balls Five balls on bifilar suspension. Also have large version with billard balls. On ball goes in, one ball comes out. Ideally linear momentum is the same. Picture: Need New Picture    Setup Requirements: Off the shelf   Equations: p = mv, conservation of linear momentum in collisions   Safety Issues: none

 1N30.15 Billiard Ball Collisions Same idea as Newton's Collision Balls device but with billard balls.                                    Setup Requirements: Off the shelf   Equations: p = mv, conservation of linear momentum in collisions   Safety Issues: none

 1N30.17 Magnetic Ball Collision This is a variation of the Newton's Balls or Billiard Balls collision devices. If used with unmagnitized balls it acts like the other collision devices. Then do it with a fifth magnetic ball rolling down the incline. One ball comes off but at high speed. Momentum of ball coming off is greater than that of the ball when non-magnetic ball is rolled down incline.     Setup Requirements: Minimal. You may want to put something to block outgoing ball. Equations: F = dp/dt. Conservation of momentum. See Physics Teacher (Vol 42 Jan 2004 p24) for explanation. Safety Issues. Damage caused by fast moving ball.

 1N30.50 Elastic vs Inelastic Collisions Demonstrate momentum transfer in elastic vs inelastic collisions. If the sharp point hits the block it will wobble but not fall over. If the rubber ball hits the block it will fall over easily. The momentum transfered to the block is approximately twice as much in the elastic case.             Setup Requirements: Hang deivce from rod. Some experimenting needed to find right place to put block. Pull object hanging from string back until back end near rod.   Equations: Sum of momentum before collision = sum of momentum after.   Safety Issues: Keep cork over sharp point when not in use.