lecture13

# lecture13 - Potential Energy The change in potential energy...

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U = - w Lift mass m with constant velocity = -mgh Potential Energy The change in potential energy is equal to minus the work done BY the body . U = - w mg

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-kx dx = - ½ 2 Potential Energy The change in potential energy is equal to minus the work done BY the body . U = - w F -kx x
Potential Energy The change in potential energy is equal to minus the work done BY the conservative force ON the body . U = - w but recall that w = K so that U = - K or U + K = 0 Any increase in PE results from a decrease in KE decrease n increase

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U + K = 0 Let’s check this for a body of mass m moving under gravity. x i x f mg w = K = K f - K i 2 2 For motion under gravity you know v2 = u2 + 2as v f 2 = v i 2 - 2gh mult by ½ m ½ m v f 2 = ½ mv i 2 -mgh +ve = - U so U + K = 0
U + K = 0 In a system of conservative forces , any change in Potential energy is compensated for by an inverse change in Kinetic energy U + K = E In a system of conservative forces , the mechanical energy remains constant

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## This note was uploaded on 11/19/2010 for the course LECTURE 1 taught by Professor Yildiz during the Spring '10 term at Berkeley.

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lecture13 - Potential Energy The change in potential energy...

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