Physics: Energy, Work and Power
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Know that energy and work are measured in joules (J), and power in watts (W).
Energy and Work are measured in Joules (J) and Power in Watts (W)
Demonstrate understanding that an object may have energy due to its motion (kinetic energy, K.E.) or its position (potential energy, P.E.), and that energy may be transferred and stored
If an object is in motion, it has kinetic energy – the faster the object moves, the greater its K.E. Another type of energy is potential energy. In this case, energy is stored due to the object’s position in a gravitational field.
Recall and use the expressions K.E. = 1/2 x m x v2 and P.E. = mgh
K.E. = 1/2 x m x v2 P.E. = mgh
Kinetic Energy Example
Objects in motion have Kinetic Energy. Moving vehicles, vibrating atoms, kicking a ball
Gravitational Energy Example
Energy stored in an object due to its position in its gravitational field. Energy of a book on the shelf, energy of a person sitting on a swing at the exact moment that the swing reaches its highest point
Chemical Energy Example
Energy stored in the bonds of chemical compounds. Chemical Reactions (Exothermic/Endothermic)
Nuclear Energy Example
Energy released during nuclear fission or fusion.
Thermal Energy Example
Energy that comes from heat. When you put ice into a hot drink.
Electrical Energy Example
Energy required to move charged particles through a conductor. Batteries
Light Energy Example
Light is energy.
Sound Energy Example
Movement of energy through the vibration of matter in longitudinal waves. Singing, yelling, screaming, crying
Give and identify examples of the conversion of energy from one form to another, and of its transfer from one place to another
Energy can transfer from one item to another but can never be ‘lost’.
Distinguish between renewable and non-renewable sources of energy.
Renewable sources of energy will never run out but non-renewable sources will run out.
Know that the Sun is the source of energy for all our energy resources except geothermal and nuclear.
The Sun is the source of energy for all our energy resources except geothermal and nuclear.
Describe how electricity or other useful forms of energy may be obtained from: • chemical energy stored in fuel • water, including the energy stored in waves, in tides, and in water behind hydroelectric dams • geothermal resources • heat and light from the Sun (solar cells and panels) • wind.
Chemical Energy stored in fuel: Energy is released through the burning of fossil fuels Water: Obtained through hydroelectric dams, tidal fences etc Heat and light from the sun: Solar Panels Wind: Wind turbines
Give advantages and disadvantages of each method in terms of reliability, scale and environmental impact
you should know this.
Recall and use the efficiency equation
efficiency = useful energy output/energy input × 100%
Recall and use W = F × d
Work = force x distance
Recall and use the equation P = E /t in simple systems.
Power = efficiency/time