JEE Main & Advanced Physics Work, Energy, Power & Collision Question Bank Work Done by Variable Force

  • question_answer A spring 40 mm long is stretched by the application of a force. If 10 N force required to stretch the spring through 1 mm, then work done in stretching the spring through 40 mm is                   [AIIMS 1998; AFMC 2000; JIPMER 2000]

    A)             84 J    

    B)             68 J

    C)             23 J    

    D)             8 J

    Correct Answer: D

    Solution :

                    Here \[k=\frac{F}{x}=\frac{10}{1\times {{10}^{-3}}}={{10}^{4}}\,N/m\] W \[=\frac{1}{2}k{{x}^{2}}=\frac{1}{2}\times {{10}^{4}}\times {{(40\times {{10}^{-3}})}^{2}}=8\,J\]

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