# Work and Energy (G481)

Work and Energy mindmap, the first half of Module 3:

- Work
- Power
- Potential energy
- Kinetic energy
- Conservation of energy

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- Created by: Anna
- Created on: 08-04-13 12:51

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- Work and Energy
- Work and Power
- Work done is the "product of the force and the distance moved by the force in the direction of travel"
- W=Fx
- F measured in Newtons (N)
- W measured in Joules (J)
- x is measured in meters (m)
- Remember to convert from cm/km/mm etc

- W=Fxcos?
- You can use a force triangle to work out these kinds of questions
- This is because it must be the distance moved IN THE DIRECTION OF THE FORCE

- Work done = Energy transferred
- E.g. moving a book from a low shelf to higher one increases it's GPE but it had some to begin with so work done is the increase in GPE NOT the total

- W=Fx
- Power is the "rate at which energy is transferred or the rate at which work is done
- P=W/t
- P is measured in Watts (W)
- "Watt is the unit of Power"

- W is work done - do not confuse with Watts (W)!
- t measured in s
- P=Fv
- W = Fx so P = Fx/t and v=x/t hence P = Fv

- P is measured in Watts (W)

- P=W/t

- Work done is the "product of the force and the distance moved by the force in the direction of travel"
- Conservation of Energy
- "Energy cannot be created or destroyed. Energy can be transferred from one form to another but the total amount of energy in a closed system will not change."
- Because of this the kinetic energy transferred to gravitational must be equal and the other way around
- GPE = KE
- 1/2mv^2=mgh
- m's cancel out
- 1/2v^2=gh
- v^2=2gh

- 1/2v^2=gh

- m's cancel out
- KE = 1/2mv^2
- KE measured in Joules (J)
- m measured in kilograms (Kg)
- v measure in meters per second (ms^-1)

- 1/2mv^2=mgh

- GPE = KE

- Kinetic Engery
- Kinetic Energy is the "energy of an object due to its motion"
- KE = 1/2mv^2
- KE measured in Joules (J)
- m measured in kilograms (Kg)
- v measure in meters per second (ms^-1)

- KE = 1/2mv^2

- Kinetic Energy is the "energy of an object due to its motion"
- Potential Energy
- elastic potential energy
- Energy stored in an extended or compressed material
- E = 1/2 ke^2
- e is the extension and is measured in m
- k is the stiffness constant
- E is measured in Joules (J)

- E = 1/2 ke^2

- Energy stored in an extended or compressed material
- gravitational potential energy
- "Energy stored by an object by virtue of its position in the Earth's gravitational field."
- GPE = mgh
- GPE measured in Joules (J)
- The Joule is defined by the work done when 1N moves an object by 1m which can be seen by looking at the units of equations. Here we have a mass, an acceleration and distance. F=ma so we have the equivalent.

- g measured in ms^-2 (acceleration due to gravity/ free fall and is = 9.81)
- The Joule is defined by the work done when 1N moves an object by 1m which can be seen by looking at the units of equations. Here we have a mass, an acceleration and distance. F=ma so we have the equivalent.

- these can be combined, see "conservation of energy.

- GPE measured in Joules (J)

- elastic potential energy

- Work and Power

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