Energy, Power and Efficiency

• What is the formula for gravitational potential energy?

  E = mgh
• What does the variable 'm' represent in the gravitational potential energy formula?

  Mass in kilograms
• What does the variable 'g' represent in the gravitational potential energy formula?

  Gravitational field strength in N/kg
• What does the variable 'h' represent in the gravitational potential energy formula?

  Height in meters
• What does the conservation of energy principle state?

  Energy cannot be created or destroyed
• What happens to energy when it is transferred to thermal energy stores?

  It increases the temperature of the substance
• What is specific heat capacity?

  Energy needed to raise 1 kg by 1 °C
• What is a closed system?

  No energy or matter is transferred in or out
• What is power defined as?

  Rate of energy transfer or work done
• How many joules are in one watt?

  One joule per second
• If a 2 W motor transfers energy faster than a 1 W motor, what does this imply?

  It lifts mass faster
• What is the formula for calculating power?

  P = W / t
• What does the efficiency of a device measure?

  Useful output energy transfer vs. total input energy
• Can any device be 100% efficient?

  No device is 100% efficient
• How can efficiency be expressed as a percentage?

  Multiply by 100
• What are the key concepts of energy, power, and efficiency?

  • Energy can be transferred, stored, or dissipated.
  • Power is the rate of energy transfer.
  • Efficiency measures useful output vs. total input.
• What are the relationships between energy, work, and power?

  • Work done is energy transferred.
  • Power is energy transferred per unit time.
  • Higher power means more energy transferred faster.