AQA GCSE Physics Energy calculations
This page covers the following topics:
When a force acts on an object and causes it to move, work is being done on the object by the force. Work done is the measure of Energy Transfer when a force (F) moves a body through a distance (d).
When an object is pushed over a distance, the work done on the object needs to be calculated in the same direction as the displacement. For example, in the diagram, the box is being pushed horizontally to the right, that means that the work done needs to be calculated using the force which is exerted horizontally. This is done with the formula W = fscos?.
When an object is moved by a force a graph can be plotted with the object’s displacement on the x-axis and the force exerted on the object on the y-axis. The amount of work done, or energy transferred, to move the object can be calculated by calculating the area under the graph.
One Watt of power is equal to one Joule (J) of energy being transferred per second (J/s). Power is calculated using the following equation:
E = mc² represents the idea that mass and energy are interchangeable. Generally this equation is used to work out changes in mass and/ or changes in energy rather than simply converting one to another. Examples of this include alpha decay and nuclear reactions.
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