Examples of Energy Transfer
- Energy transfers occur all the time in various everyday circumstances
- Some common situations include when:
- An object projected upwards or up a slope
- A moving object hitting an obstacle
- An object being accelerated by a constant force
- A vehicle slowing down
- Bringing water to a boil in an electric kettle
An Object Projected Upwards
- Before the ball is thrown upwards, the person holding the ball has energy in their chemical store
- When the ball is thrown, some of that energy is transferred to the kinetic store of the ball as it begins to move upwards
- As the height of the ball increases, energy from the kinetic store of the ball is transferred to its gravitational potential store
A Moving Object Hitting an Obstacle
- When an object, such as a car, is moving, energy in the chemical store of the fuel is transferred to the kinetic store of the car
- If the object hits an obstacle, such as a car hitting a wall, the speed of the car will decrease very quickly
- Therefore, the energy in its kinetic store will decrease
- In this scenario, most of the energy from its kinetic store is transferred to the thermal store of the surroundings (dissipated)
- Energy is transferred mechanically to the thermal store of the wall (the force of the car on the wall)
- Energy is also transferred by heating to the thermal store of the air as the sound waves transfer energy away from the system (causing the air particles to vibrate)
A Vehicle Being Accelerated by a Constant Force
- When an object, such as a vehicle is stationary, it has energy in the chemical store of the fuel
- When the vehicle speeds up or accelerates, the energy is transferred to the kinetic store of the car
A Vehicle Slowing Down
- When a vehicle is moving, it has energy in its kinetic store
- As it slows down or decelerates, energy is transferred to the thermal store of the surroundings (dissipated)
- This energy is transferred by heating due to friction between the tyres and the ground, and due to friction between the brakes and the brake pads
- Energy is also transferred by heating as the sound waves transfer energy away from the system (making the air particles vibrate)
Boiling Water in an Electric Kettle
- When an electric kettle boils water, energy is transferred electrically from the mains supply to the thermal store of the heating element inside the kettle
- As the heating element gets hotter, energy is transferred by heating to the thermal store of the water
