Examples of Energy Transfer (OCR Gateway GCSE Physics: Combined Science)

• 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