Fluid Mechanics

JEE Main level, numerical answer, medium

31 of 192

Question 31 of 192

A hydraulic press can lift 100kg100kg when a mass mm is placed on the smaller piston. It can lift kg when the diameter of the larger piston is increased by 44 times and that of the smaller piston is decreased by 44 times keeping the same mass mm on the smaller piston.

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Answer: 25600

Using Pascals law,

100×gA2=mgA1...(1)\dfrac{100\times g}{{A}_{2}}=\dfrac{mg}{{A}_{1}}...\left(1\right)
Let
mm mass can lift M0{M}_{0} in second case then
M0g16A2=mgA1/16...(2)\dfrac{{M}_{0}g}{16{A}_{2}}=\dfrac{mg}{{A}_{1}/16}...\left(2\right)
{SinceA=πd24}\left\{SinceA=\dfrac{\pi {d}^{2}}{4}\right\}
From equation
(1)\left(1\right) and (2)\left(2\right) we get
M016.100=16\dfrac{{M}_{0}}{16.100}=16
⇒M0=25600kg\Rightarrow {M}_{0}=25600kg

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