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ENERGY RESOURCES AND ENERGY TRANSFERS, sanky-diagram-400x207 - Coggle…
ENERGY RESOURCES AND ENERGY TRANSFERS
Describing energy transfers involing energy stores
Energy stores
: chemical, kinetic, gravitational, elestic, thermal, magnetic, electrostatic, nuclear
Energy transfers
: mechanically, electrically, by heating, by radiation (light and sound)
Conservation of energy
Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed .
Efficiency calculations
Total energy input (J)
Uselful energy output (J)
Efficiency = uselful energy output / total energy input x100 (EFF = uselful out / total in x100)
Sankey diagrams
The energy flow is shown by arrows whose width is proportional to the amount of energy involved.
The wasted and useful energy outputs are shown by different arrows.
You can look at OneNote for a clearer image and explanation!
Work done calculations
Work done = Force x distance (W=Fxd)
Work done (J)/(Nm)
Force (N)
Distance (m)
Rearanging:
Force = work done / distance (F = w.d / d)
Distance = work done / force (d = w.d / F)
Key info
Work done is equal to energy transferred
Describe power as the rate of transfer of energy or the rate of doing work
Gravitation potential energy calculations
mass (kg)
gravity (N/kg)
Gravitation potential energy (J)
height (m)
Gravitation potential energy = mass x gravity x height (GPE = m x g x h)
Rearanging:
gravity = energy / mass x height (g = En / m x h)
height = energy / gravity x mass (h = En / g x m)
mass = energy / height x gravity (m = En / h x g)
Kinetic energy calculations
mass (kg)
Kinetic energy (J)
Velcity (m/s)
Rearanging
velocity = √2 x ke / m
mass = 2 x ke / v^2
Kinetic energy = 1/2 x mass x velocity^2 (KE = 1/2 x m x v^2)
Power calculations
Power (w)/(J/s)
Energy transfered (J)
Power = Energy transfered / Time
Time (s)
Rearanging:
Time = Energy transfered / Power (t = E / p)
Energy transfered = Power x time (E = P x t)
Links between GPE, KE, and W
Work done is equal to the change in kinetic energy or gravitational potential energy.
If work is done on an object, its KE or GPE will increase.
Conversely, if work is done by an object, its KE or GPE will decrease.
