ME 242 Lecture 17 03.09

# ME 242 Lecture 17 03.09 - ME 242 Dynamics March 9 2009...

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1 ME 242 Dynamics March 9, 2009 Eric Wang Today’s Key Concepts Chapter 4: Energy of Particles Work Kinetic Energy The Work-Energy Method Motivation Using the Work-Energy Method, we will be able to find an object’s speed or position at some time in the future without having to perform any integrations Work • Differential form: dW = F dr Work • Using Path coordinates dW = F dr = F t ds W = F t ds Location 1 to Location 2: W 1 2 = F t ds s 1 s 2 = m ˙ ˙ s ds s 1 s 2 = m ˙ s d ˙ s ˙ s 1 ˙ s 2 = m ˙ ˙ s ds s 1 s 2 adx = vdv ˙ ˙ s ds = ˙ s d ˙ s

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2 Kinetic Energy W 1 2 = m ˙ s d ˙ s ˙ s 1 ˙ s 2 = m 1 2 ˙ s 2 2 ˙ s 1 2 ( ) = 1 2 mv 2 2 1 2 mv 1 2 = KE 2 KE 1 KE = 1 2 mv 2 Work-Energy W 1 2 = KE 2 KE 1 W 1 2 = F dr r 1 r 2 KE 2 = KE 1 + F dr r 1 r 2 Work vs. Momentum • Vector Equation • Scalar Equation 1 2 mv 2 2 = 1 2 mv 1 2 + F dr s 1 s 2 mv
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## This note was uploaded on 09/19/2009 for the course ME 242 taught by Professor Kam during the Spring '06 term at Nevada.

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ME 242 Lecture 17 03.09 - ME 242 Dynamics March 9 2009...

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