Class 8: Kinetic energy work done and Class 8: Kinetic energy, work - - PowerPoint PPT Presentation

class 8 kinetic energy work done and class 8 kinetic
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Class 8: Kinetic energy work done and Class 8: Kinetic energy, work - - PowerPoint PPT Presentation

Class 8: Kinetic energy work done and Class 8: Kinetic energy, work done, and conservative force Three pillars of Newtonian mechanics p Newtons L N aw of Motion M Newtonian Mechanics Conservati ion of Energy Conservat ion of Momentum m


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SLIDE 1

Class 8: Kinetic energy work done and Class 8: Kinetic energy, work done, and conservative force

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SLIDE 2

Three pillars of Newtonian mechanics p

Newtonian Mechanics ion of aw of ion of m Conservati Energy Newton’s L Motion Conservat Momentum N M

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SLIDE 3

Ki ti E Kinetic Energy

2

1 T

2

mv 2 T =

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SLIDE 4

W k d Work done

1 `B

Work done by F

s d F W

B B A

v ⋅ = =

s d F W

A B A

F ds

A B

s d F

  • s

d F ⋅ = ⋅

∫ ∫

v v

A F

A B B A B A

W W

→ → =

for the same path.

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SLIDE 5

Conservative Force If F is a function of position: F(r) B If WA→B is path i d d i

1 `

independent, F is conservative. If WA→B is path d d F i A dependent, F is non‐ conservative.

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SLIDE 6

Conservative Force If F(r) is conservative

  • 1. WA→A = 0

2. F = × ∇ v A

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SLIDE 7

Two Important Equations for Vector Analysis Two Important Equations for Vector Analysis

) F ( . 1 = × ∇ ⋅ ∇ v ) ( 2. = Φ ∇ × ∇

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SLIDE 8

Potential Energy If F(r) is conservative, there exist a scalar f i U( ) h function U(r) so that

U F ∇ v

U i ll d h i l i

U

  • F

∇ =

U is called the potential energy at point r. N h U i i i i f i Note that U is not unique in satisfying above equation. It requires “boundary diti ” t fi it condition” to fix it.