Conservation Of Energy Flashcards
(23 cards)
What is the formula for gravitational potential energy?
GPE = mass × gravitational field strength × change in height (ΔGPE = m × g × Δh)
What is the formula for kinetic energy?
KE = ½ × mass × velocity² (KE = ½ × m × v²)
What does conservation of energy mean?
Energy cannot be created or destroyed, only transferred or stored differently.
Describe energy changes when an object is projected upwards.
Kinetic energy is transferred to gravitational potential energy.
Describe energy changes when a moving object hits an obstacle.
Kinetic energy is transferred to sound, thermal energy, and deformation.
Describe energy changes when an object is accelerated by a constant force.
Work done by the force transfers energy into kinetic energy.
Describe energy changes when a vehicle slows down.
Kinetic energy is transferred into thermal energy in the brakes and surroundings.
Describe energy changes when boiling water in an electric kettle.
Electrical energy is transferred into thermal energy in the water.
What happens to total energy in a closed system?
It remains constant — energy is conserved.
Why do mechanical processes become wasteful?
They cause a rise in temperature losing energy to surroundings as heat.
How is energy lost in system changes?
Less useful energy, often thermal, lost to surroundings.
How can unwanted energy transfer be reduced?
Through lubrication or thermal insulation.
What is the formula for efficiency?
efficiency = useful energy transferred / total energy supplied
How can efficiency be increased?
By reducing wasted energy through insulation, streamlining, or lubrication.
Name some renewable energy resources.
Wind, hydroelectricity, tidal, solar, biofuel.
Name some non-renewable energy resources.
Fossil fuels and nuclear fuel.
How are energy sources used differently?
Some are used for electricity generation, heating, or transport.
What is the trend in use of fossil fuels?
Decreasing due to environmental concerns and finite supply.
What is the trend in use of renewables?
Increasing due to sustainability and reduced carbon emissions.
What is meant by ‘wasted energy’?
Energy that is not usefully transferred and often lost as heat.
What is meant by ‘useful energy’?
Energy transferred in a way that helps accomplish the desired task.
What is the unit of energy?
The joule (J).
Why is energy efficiency important?
To reduce waste, save cost, and limit environmental impact.
