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Velocity ratio of simple machine is the ratio of distance travelled by effort to the distance travelled by load in the machine. The efficiency of a simple machine is defined as the ratio of useful work done by machine (output work) to the total work put into the machine (input work).

Explanation:

Mechanical advantage is the ratio of load to effort of machine or we can say it is the ratio of output of machine to the input of the machine. Velocity ratio is also defined as velocity of effort to the velocity of load. Efficiency (η)=M.

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d.) gravity pulled particles of dust and gas together to form planets.

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