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7th Class Science Related to Competitive Exam Question Bank Work and energy

  • question_answer
    DIRECTIONS: The questions in this segment consist of two statements, one labeled as ?Assertion A? and the other labeled as ?Reason R?. You are to examine these two statements carefully and decide if the Assertion A and Reason R are individually true and if so, whether the reason is a correct explanation of the assertion. Select your answers to these items using codes given below Assertion (A): When a gas is allowed to expand, work done by gas is positive. Reason (R): Force due to gaseous pressure and displacement (of piston) are in the same direction.

    A) Both A and R are true and R is the correct explanation of A.

    B) Both A and R are true but R is not the correct explanation of A.

    C) A is true but R is false.

    D) A is false but R is true.

    Correct Answer: A

    Solution :

        Since the gaseous pressure and the displacement (of piston) are in the same direction. Therefore \[\theta =0{}^\circ \] \[\therefore \] Work don\[=Fs\cos \theta =Fs=P\]Positive Thus during expansion work done by gas is positive.


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