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Work, Energy and Power.

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Presentation on theme: "Work, Energy and Power."— Presentation transcript:

1 Work, Energy and Power

2 Reaction Rocket

3 Work A force is said to do work if, when acting, there is a displacement of the point of application in the direction of the force. Measure of energy transfer that occurs when an object is moved over a distance by an external force at least part of which is applied in the direction of the displacement.

4 Work (Constant F)

5 Dot Product

6 Linear Work (F constant)
W = F Dr cosq F q r

7 Linear Work (F not constant)

8 Work by a non-constant force
Work is the area under the F vs. x curve

9 Work = change in mechanical energy
Work Energy Theorem W = DE Work = change in mechanical energy

10 The sum of the potential and kinetic energies
Mechanical Energy The sum of the potential and kinetic energies U = potential energy K = kinetic energy E = U + K

11 Conservative Force A force is conservative if:
The work done between point A and B is independent of the path The work done around any closed path is zero

12 Non-Conservative Force
Friction

13 Conservation of Mechanical Energy
If the only work done on an object is by a conservative force, then the mechanical energy of the object is conserved.

14 Conservation of Energy
The total energy of an isolated system is conserved. The energy can be transferred from one object to another or transformed from one form to another, but energy cannot be created or destroyed.

15 Potential Energy

16 Work Done By Gravity h mg

17 Gravitational Potential Energy

18 Hooke’s Law x

19 Work Done By A Spring

20 Elastic Potential Energy

21 Work by Net Force v2 = 20 m/s v1 = 10 m/s

22 Kinetic Energy

23 Net Work = change in kinetic energy
Work Energy Theorem, Pt. 2 Wnet = DK Net Work = change in kinetic energy

24 Power

25 Power (alternate equation)

26 Energy Diagram A diagram that displays energy as a function of displacement Normally used to display potential energy

27 General Form Unstable Equilibrium Neutral Equilibrium

28 Circular Motion


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