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8th Class Science Force and Pressure Question Bank Force and Pressure

  • question_answer
    The surface area of the base of a brick X is\[\text{100 c}{{\text{m}}^{\text{2}}}\]. The surface area of the base of the brick Y is\[\text{250 c}{{\text{m}}^{\text{2}}}\]. Each brick weighs 100 N. Which of the following is correct if \[{{\text{P}}_{1}}\] and \[{{\text{P}}_{2}}\]are the pressures exerted by the bricks X and Y respectively?

    A) \[{{P}_{1}}={{P}_{2}}\]               

    B) \[{{P}_{1}}>{{P}_{2}}\]   

    C) \[{{P}_{1}}<{{P}_{2}}\]               

    D) \[{{P}_{1}}={{P}_{2}}=0\]

    Correct Answer: B

    Solution :

    For \[\text{X, }{{\text{F}}_{1}}\text{=100 N, }{{\text{A}}_{1}}\text{=100 c}{{\text{m}}^{\text{2}}}\] \[\therefore {{P}_{1}}=\frac{{{F}_{1}}}{{{A}_{1}}}=\frac{100}{100}=1Nc{{m}^{-2}}\] For \[Y,{{F}_{2}}=100\,\,N,\,\,{{A}_{2}}=250c{{m}^{2}}\] \[\therefore {{P}_{2}}=\frac{{{F}_{2}}}{{{A}_{2}}}=\frac{100}{250}=0.4Nc{{m}^{-2}},\,\,Hence,\,\,{{P}_{1}}>{{P}_{2}}\]


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