Chapter 5 - Work, Energy and Power

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A level Physics (5 - Work, energy, power) Mind Map on Chapter 5 - Work, Energy and Power, created by Kieran Lancaster on 12/20/2017.
Mind Map by Kieran Lancaster, updated more than 1 year ago
 Created by Kieran Lancaster over 6 years ago
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Chapter 5 - Work, Energy and Power
1. Work done and energy
1. Work done (Units Nm/J) = Force X distance moved in the direction of the force
1. Work done = Energy transferred (Energy is the capacity to do work)
1. W=Fx
2. When force is applied at an angle, the following formula can be used
3. Conservation of energy
1. Energy is the capacity for doing work
1. "Potential" energy can be stored, and converted into other forms. This includes G.P.E, elastic and electric. Non potential energy can only be transferred
1. Principle of conservation of energy - The total energy of a closed system remains constant, energy can never be created or destroyed, only transferred from one form to another
2. K.E and G.P.E
1. K.E is directly proportional to the mass of the object, and directly proportional to the speed squared
1. Gravitational Potential energy - The capacity for doing work as a result of an objects position in a gravitational field
1. This formula can only be used for a UNIFORM gravitational field (i.e close to Earth's surface) where g can be assumed to remain constant
1. It is gained with height
1. Using the idea of W=Fd, the force is Weight (mg), and the distance is the vertical height travelled (h), meaning you get G.P.E = mgh
2. G.P.E can be converted to K.E, e.g with a waterfall or rollercoaster. By putting them equal to each other, the final velocity v does not depend on the mass of the object. It's only true if there are no resistive forces
2. Power and efficiency
1. Power is the rate of work done (Or rate of energy transfer). Units are Js^-1, or Watts
1. Sometimes, a constant force has to be exerted to maintain speed, e.g a car on a road.
1. For the car, the net force is zero, since the power of the engine is equal to the rate of work done against frictional forces
1. This equation can be used for a variety of situations, like above
2. All energy in a closed system is conserved, but it does not mean all energy is converted into useful output energy

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