Examples of Energy Transfer (AQA GCSE Physics: Combined Science)

• Different types of energy transfers occur all the time in various everyday circumstances
• Some common situations include
  • When an object is projected upwards
  • When a moving object hits an obstacle
  • When an object is accelerated by a constant force
  • When a vehicle speeds up or slows down
  • When water is brought 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 the 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 car, the wall and 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 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 on 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 a Kettle

• When an electric kettle boils water, energy is transferred by electrical working from the mains 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