10.2 Fields at work

Gravitational potential energy

Electrostatic potential energy

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The gravitational potential energy of an object at a point P is equal to the work done required to take the object from infinity to the point P.

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The electric potential energy can be defined as the capacity for doing work by a change in position of the positive test charge. (As gravitational forces are attractive, the work done required to bring an object from infinity to any point is negative)

Potential gradient

Gravitational potential gradient
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It is the slope of a graph which plots the gravitational potential against the distance from the mass. (Field strength)

Electrostatic potential gradient
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Potential difference

Electrostatic potential difference
the amount of work done in moving unit mass from one point to another point against the gravitational force of attraction

Gravitational potential difference
the work done by moving a positive test charge from one point to another in an electric field.

Escape speed

Escape speed it the minimum speed required for an object launched from the surface of a planet to reach infinity.

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Orbital

Orbital period

Orbital speed

Occurs when centripetal force is equal to gravitational attraction force

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Kepler's third law


The ratio of the square of an object's orbital period with the cube of the semi-major axis of its orbit is the same for all objects orbiting the same primary.


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Orbital Energy

Gravitational potential energy
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Kinetic energy
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Total Energy
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