JEE Main & Advanced Physics Fluid Mechanics, Surface Tension & Viscosity / द्रव यांत्रिकी, भूतल तनाव और चिपचिपापन Question Bank Self Evaluation Test - Mechanical Properties of Fluids

  • question_answer
    In a hydraulic lift, compressed air exerts a force \[{{F}_{1}}\] on a small piston having a radius of 5 cm. This pressure is transmitted to a second piston of radius 15 cm. If the mass of the load to be lifted is 1350 kg, find the value of\[{{F}_{1}}\]? The pressure necessary to accomplish this task is

    A) \[1.4\times {{10}^{5}}Pa\]

    B) \[12\times {{10}^{5}}Pa\]

    C) \[1.9\times {{10}^{5}}Pa\]

    D) \[1.9Pa\]

    Correct Answer: C

    Solution :

    [c] Since pressure is transmitted undiminished throughout the fluid (Pascal's law) \[{{F}_{1}}=\frac{{{A}_{1}}}{{{A}_{2}}}{{F}_{2}}=\frac{\pi (5\times 5)}{\pi (15\times 15)}(1350\times 9.81)\] \[\approx \,\,1.5\times {{10}^{3}}N\] The air pressure that will produce this force is  \[P=\frac{{{F}_{1}}}{{{A}_{1}}}=\frac{1.5\times {{10}^{3}}}{\pi {{(5\times {{10}^{-2}}m)}^{2}}}=1.9\times {{10}^{5}}Pa\]


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