Energy, Work and Power
Energy
Capacity to do work (J)
-KE
-CPE
-GPE
-EPE
-EE
-Light
-Thermal
-Nuclear
Principle of Conservation of Energy states that energy can't be destroyed or created, can only be converted form one form to another or transferred from a body to another. TOtal energy is constant.
Effeciency
Total energy input=useful energy output + wasted energy output
Effeciency= useful energy output/ total energy input x 100%
Work
Work done by a constant force on an object is the product of the force and the distance moved by the object in the direction of the force
W=Fd, where W is work done (J), F is constant force (N), d is distance moved by the obj in the direction of the force (m)
Energy is needed to do work, which is done when an obj moves under the influence of a Force
Kinetic energy
Energy which a body possesses by virtue of being in motion
KE=1/2mv^2, where m is mass (kg), v is speed of body (m/s)
Power
P=W/t=E/t, where P is power (W), W is work done (J), E is energy converted (J), t is time taken (s)
Power is rate of work done/ rate of energy conversion (W)
Potential energy
CPE
EPE
GPE
GPE=mgh, where m is mass (kg), g is gravitational field strength (m/s^2), h is height (m)
Position of obj above group
Energy stored in a substance due to the position of atoms
Energy stored in an object due to it's elastic deformation