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# Tag Archives: circular path

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## Why gravitational force of attraction is necessary for a satellite to revolve around earth?

The question was posted by Raj Kumar.

The satellite has a velocity. To revolve around, the direction of velocity must change. In the absence of a force it can move only in a straight line. It is the gravitational force which helps the satellite top change direction and revolve around the earth.

In other words, for a satellite to revolve in a circular path, a centripetal force is required. This centripetal force is provided by the force of gravitation only.

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## Misconception on Work and energy conservation

It is said that when work is done energy is lost. But when a man runs in a circular path and reaches the starting point, then the work done is zero but energy is lost. (Divyam asked)
Answer: The work done here is not zero, work is done and energy is spent to overcome friction. Though he is reaching the same point, he is moving against a non conservative force, friction (where the work done in a closed path is not zero)