IGCSE Physics Revision Notes Energy Work Power

1.7.1 Energy

•  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.

EXTENDED OBJECTIVES

• Recall and use the equation for kinetic energy Ek = 1/2mv²
•  Recall and use the equation for the change in gravitational potential energy ?E p = 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,

1.7.2 Work:

CORE OBJECTIVES:

•  Understand that mechanical or electrical work done is equal to the energy transferred
•  Recall and use the equation for mechanical working W = Fd = ?E

1.7.3 Energy resources

CORE OBJECTIVES:

• 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 2
• 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

EXTENDED/SUPPLEMENT:

• Know that radiation from the Sun is the main source of energy for all our energy resources except geothermal, nuclear and tidal
• Know that energy is released by nuclear fusion in the Sun
• Know that research is being carried out to investigate how energy released by nuclear fusion can be used to produce electrical energy on a large scale
•  Define efficiency as:
• (a) (%) efficiency = (useful energy output) (total energy input) (× 100%)
• (b) (%) efficiency = (useful power output) (total power i