1.1.2 Examples of Energy Transfer

• Energy transfers occur when an object is projected upwards, a moving object hits an obstacle, an object is accelerated by a constant force, a vehicle speeds up or slows down, or water is brought to a boil in an electric kettle.
• When an object is projected upwards, the person holding the object has energy in their chemical store.
• When the object is thrown, some of that energy is transferred to the kinetic store of the object as it begins to move upwards.
• As the height of the object increases, energy from the kinetic store of the object is transferred to its gravitational potential store.
• When a moving object hits an obstacle, such as a car hitting a wall, the speed of the car will decrease very quickly, transferring most of the energy from its kinetic store 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) and also 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).
• 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.
• When a vehicle is slowing down, it has energy in its kinetic store.
• As the vehicle slows down or decelerates, energy is transferred to the thermal store of the surroundings (dissipated).
• 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).
• 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.