Phys30+Momentum

= Welcome to the Physics 30 Momentum page! =

= The Solar Sail = http://en.wikipedia.org/wiki/Solar_sail

====The solar sail is an example of a special property of light. Light particles called photons have zero mass, although they do carry momentum. This sounds impossible because we know P=mv, however Einstein showed that matter and energy are equivalent with his famous formula E=mc 2. A consequence of this was that anything with energy must also carry with it momentum; meaning that light did have momentum. This property of light has been experimentally verified, and is the property of light that pushes the solar sail. Photons strike the sail and cause it to move, in accordance with conservation of momentum.====

A Game of Pool


The above photo is one taken from a game in the National Amateur Pool League (NAPL). In a game of pool, physics plays an important role, as one can anticipate their shot by taking into consideration the principle, conservation of momentum. The person in the photo is attempting to shoot the cue ball into the nine ball (the yellow ball), striking it on the surface facing towards the player. By doing this, the ball will go into the corner pocket winning him the game of 9-ball he is participating in. The shot is sunk, and he wins the game, the ball entering the pocket at 5m/s. If the cue ball struck the 9- ball at an angle of [10*E of S], what was the velocity of the cue ball? Note - the mass of the balls are 0.17kg for the cue ball, and 0.16kg for the 9-ball. Assume no friction acts upon the balls.\

Catching a baseball- Chris

The physics principle involved in this senario is conservation of momentum. The ball has momentum as it comes fying towards home base. That momentum is conserved as the ball hits the glove. Since the man has a bigger mass, his hand only gets pushed back at a small velocity until the ball finally come to rest. The principles of impulse are in affect here. Since the ball has a longer time and a larger distance to come to rest in the glove, it shows how the catcher is able to catch the ball without breaking his hand. If the man accidently missed the catch and it hit him in the face, he may fall back at a larger velocity because he is not absorbing the throw. Since the time and distance is less, the force at which the ball hits the man is more damaging.