Physics

• A moving object always has energy in its kinetic energy store.
• Resistance= potential difference/current
• Power= energy transferred every second by an electrical appliance
• The image in a mirror cannot be touched so it is virtual
• waves changing direction when they cross a boundary is called refraction.
• What unit is used for gravitational potential energy?


  Joules
• As the speed of an object increases, the kinetic energy of the object increases
• battery stores chemical energy
• A wind turbine transfers energy from kinetic energy stores
• gravitational potential energy = mass × gravitational field strength × height
• mass = gravitational potential energy / (gravitational field strength × change in height)
• Efficiency = useful energy output / total energy input = 75 J / 100 J = 75%
• All objects that are moving will have some energy in their kinetic energy store.
• Efficiency = (useful energy output / total energy input) × 100
• Scientists say renewable resources do help the environment, because they have fewer harmful emissions.
• Finite resources are those that cannot be replaced at a similar rate to the rate at which they are used. Crude oil takes millions of years to form.
• Fossil fuels cannot be replaced at a similar rate to the rate at which they are used up, so they are a non-renewable resource.