# ch3(1).pdf - Vern J Ostdiek Donald J Bord Conservation Laws...

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1/27/20191Vern J. OstdiekDonald J. BordConservation LawsPRINCIPLESThe total mass in an isolated system is constant.A conservation law states that the total amount of a certain physical quantity present in a system stays constantEx: aerial refueling. One aircraft, called a tanker, pumps fuel into a second aircraft while both are in flight. Isolated system: total mass of both aircrafts is constantIf the receiving aircraft gains 2,000 kilograms of fuel, the tanker loses 2,000 kilograms of fuel. Linear MomentumDEFINITIONLinear Momentum: The mass of an object times its velocity. Linear momentum is a vector.linear momentum = mvLinear momentum incorporates both mass and motion.Anything that is stationary has zero momentum. The faster a body moves, the larger its momentum. A heavy object moving with a certain velocity has more momentum than a light object moving with the same velocity.DEFINITION
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1/27/20193Example 3.1Estimate the average force on a golf ball as it is driven off a tee. The ball’s mass is 0.045 kg, and it leaves the club head with a horizontal speed of 50 m/s (110 mph). High-speed photographs indicate that the contact time is about 5 milliseconds (0.005 s). Ignore any spin imparted to the ball upon impact.Conservation of Linear Momentum: CollisionsLAWSLaw of Conservation of Linear Momentum: The total linear momentum of an isolated system is constant.For this law, an isolated system means that there are no outside forces causing changes in the linear momenta of the objects inside the system. The momentum of an object can change only because of interaction with other objects in the system. Conservation of Linear Momentum: CollisionsOnce the cue ball on a pool table has been shot, the pool table and the balls form an isolated system. If the cue ball collides with another ball initially at rest, its momentum is decreased. The momentum of the second ball is increased, but the total linear momentum of the system containing both balls remains the same.
1/27/20194Conservation of Linear Momentum: CollisionsLAWSThe total linear momentum of the objects in a system before the collision is the same as the total linear momentum after the collision.