ASTR 1110 book summary - ch.4.3

ASTR 1110 book summary - ch.4.3 - Astronomy Book Notes 4.3...

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Astronomy – Book Notes 4.3 Conservation Laws in Astronomy Three important conservation laws for astronomy: 1. Law of Conservation of Momentum: the total momentum of interacting objects cannot change as long as no external force is acting on them. ( t heir total momentum is conserved ) - Reason why objects move at a constant velocity when no force is acting on them. - An individual object can gain or lose momentum ONLY if some other object’s momentum changes by a precisely opposite amount. - Example : fire a rocket engine the total momentum of the rocket and the hot gases it shoots out the back, must be the same. o (amount of forward momentum rocket gains – equal – to amount of backward momentum in the gas that shoots out the back. o That is why forces between the rocket and the gases are always equal and opposite. - Explains Newton’s first law: o If no net force acts on an object, there is no way for the object to transfer any momentum to/from any other object. - Absence of a net force object’s momentum must remain unchanged o Object must continue to move exactly as it has been moving. 2. Law of Conservation of Angular Momentum: As long as there is no external torque, the total angular momentum of a set of interacting objects cannot change. An individual object can change its angular momentum only by transferring some angular momentum to or from another object. o
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This note was uploaded on 02/27/2008 for the course ASTR 1110 taught by Professor Hornstein during the Spring '08 term at Colorado.

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ASTR 1110 book summary - ch.4.3 - Astronomy Book Notes 4.3...

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