AQA GCSE Physics Energy in systems
This page covers the following topics:
An energy system is a series of objects that are able to interact with one another. There are 3 different types of energy system: open, closed and isolated.
Changes in energy within a system can occur when a force brings about a change in an objects speed, shape or height. Changes in energy can be calculated in a number of ways, for mechanical work it is important to understand how to calculate kinetic energy, gravitational potential energy and elastic potential energy.
As a current flows through a wire, electrons pass through the wire and transfer energy around a circuit from an energy source to a battery. The amount of energy transferred each second (power) can be calculated with the following two different equations:
There are three ways that heat (or thermal energy) is transferred from one object to another: conduction, convection and radiation. The type of heat transfer in a system depend on the type of matter in the energy system.
A skydiver with a weight of 65 kg jumps from a plane, they reach a speed of 53 m/s before pulling their parachute. What is the gain of kinetic energy of the skydiver? Give your answer in kJ correct to one decimal place.
Electrical power can be supplied at a high voltage with a low current, or with a low voltage and high current. Which of these combinations of current and voltage is the most efficient for transferring energy? Explain your answer.
A beaker of 500 g of water is at 25°C and is heated up to 55°C. The specific heat capacity of water is 4200 J/kg°C. What is the change in thermal energy of the water for this change in temperature? Give your answer in kJ correct to one decimal place.
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