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CramPuppy - Free Revision Notes » Gcse » Physics » Weight / Gravity / Energy / Work

Weight / Gravity / Energy / Work

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Weight and Gravity

The weight of an object is the force of gravity acting on it. It is calculated using the following formula:

    Weight (N)   =   Mass (kg)   x   g (N/kg or m/s2)
This force of gravity is explained by considering the earth to be surrounded by a gravitational field. The strength of this field is the force acting upon a mass of 1kg and this is 9.8 N/kg near the surface.

Energy and Work

Energy exists in many different forms and can be changed from one form into another. There are 2 main types of energy:

  • Potential Energy (PE) - some examples are:
          Gravitational PE (GPE) - energy stored due to position (e.g. being high up)
          Elastic PE - energy stored in a stretched spring
          Chemical PE - energy stored in a fuel
          Magnetic PE - energy stored in a magnetic field
  • Kinetic Energy (KE)
Kinetic Energy is motion / movement energy. Other forms of energy are heat, light, sound, electrical, and nuclear.

Work is done when energy is changed (transferred) from one form into another. (e.g. in lifting a weight up, energy is transferred from chemical energy (in the person's muscles) to GPE)

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by: Guest
Total views: 1715
Word Count: 242
Date: Thu, 9 Aug 2007 Time: 12:00 AM
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