Momentum, Work, Energy & Power

Define momentum as mass × velocity; recall and use the equation p = mv

Define impulse as force × time for which force acts; recall and use the equation impulse = F∆t = ∆(mv)

Apply the principle of the conservation of momentum to solve simple problems in one dimension

Define resultant force as the change in momentum per unit time; recall and use the equation ∆p F = ∆t

State that energy may be stored as kinetic, gravitational potential, chemical, elastic (strain), nuclear, electrostatic and internal (thermal)

Describe how energy is transferred between stores during events and processes, including examples of transfer by forces (mechanical work done), electrical currents (electrical work done), heating, and by electromagnetic, sound and other waves

Know the principle of the conservation of energy and apply this principle to simple examples including the interpretation of simple flow diagrams

Recall and use the equation for kinetic energy 1 2 Ek = mv 2

Recall and use the equation for the change in gravitational potential energy ∆Ep = mg∆h

Know the principle of the conservation of energy and apply this principle to complex examples involving multiple stages, including the interpretation of Sankey diagrams

Understand that mechanical or electrical work done is equal to the energy transferred

Recall and use the equation for mechanical working W = Fd = ∆E

Describe how useful energy may be obtained, or electrical power generated, from: (a) chemical energy stored in fossil fuels (b) chemical energy stored in biofuels (c) water, including the energy stored in waves, in tides and in water behind hydroelectric dams (d) geothermal resources (e) nuclear fuel (f) light from the Sun to generate electrical power (solar cells) (g) infrared and other electromagnetic waves from the Sun to heat water (solar panels) and be the source of wind energy including references to a boiler, turbine and generator where they are used

Describe advantages and disadvantages of each method in terms of renewability, availability, reliability, scale and environmental impact

Understand, qualitatively, the concept of efficiency of energy transfer

Know that radiation from the Sun is the main source of energy for all our energy resources except geothermal, nuclear and tidal

Define efficiency as: (a) (useful energy output) (%) efficiency = (× 100%) (total energy input) (b) (useful power output) (%) efficiency = (× 100%) (total power input) recall and use these equations

Define power as work done per unit time and also as energy transferred per unit time; recall and use the equations W (a) P = t ∆E (b) P = t