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15 May 2011 16:43:34 IST

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Find the mechanical advantage of a machine ,which has a velocity ratio of 3:2,and efficiency75%

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Find the mechanical advantage of a machine ,which has a velocity ratio of 3:2,and efficiency75%

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saharsha kumar keshkar

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Joined: 7 Aug 2008

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15 May 2011 19:58:34 IST

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Mechanical Advantage:

The ratio, load/effort is called mechanical advantage of a machine. The mechanical advantage should be greater than one. If, in a machine, the ratio is less than one, it would be more accurate to call is mechanical disadvantage.

Velocity Ratio:

The ratio

is called the velocity ratio of a machine. The two distances are moved in the same interval of time, so they are proportional to the velocities of the effort and load.

P×d₁ = W×d₂ in a perfect machine.

where d₁ and are d₂ are the distances moved by effort P and load W respectively. Hence, in a perfect machine the mechanical advantage is equal to velocity ratio.

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Efficiency of Machine:

In all machines some work is always wasted friction. The result of it is that the work done by the effort in a given time, called total work or work input (= p × d₁) is always greater than the work done on the load (= W × d₂) called useful work or work output. The difference of the latter from the former = lost work (Pd₁-Wd₂).

The ratio

is called efficiency of machine. It is also defined as the ratio

In any actual machine the efficiency is always less than one but in a perfect or ideal machine in where there is no friction at all the efficiency is equal to unity.

efficiency of machines

Or Mechanical advantage = Efficiency × velocity ratio

i.e. M.A. =Velocity Ratio × η

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i think solution is clear now or numerical value might be

3/2 * .75== 3/2 * 3/4== 9/8==

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