A moving railway compartment has a spring of constant k fixed to its front wall. A boy stretches this spring by distance x and in the mean time the compartment moves by a distance s. The work done by boy w.r.t. earth is A. (a) `1/2kx^2`B. (b) `1/2(kx)(s+x)`C. (c) `1/2kxs`D. (d) `1/2kx(s+x+s)`

A moving railway compartment has a spring of constant k fixed to its f

1.	A moving railway compartment has a spring of constant k fixed to its front wall. A boy stretches this spring by distance x and in the mean time the compartment moves by a distance s. The work done by boy w.r.t. earth is A. (a) `1/2kx^2`B. (b) `1/2(kx)(s+x)`C. (c) `1/2kxs`D. (d) `1/2kx(s+x+s)`
Answer» Correct Answer - A Total work done in equal to the energy stored in the spring.

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A moving railway compartment has a spring of constant k fixed to its front wall. A boy stretches this spring by distance x and in the mean time the compartment moves by a distance s. The work done by boy w.r.t. earth is A. (a) `1/2kx^2`B. (b) `1/2(kx)(s+x)`C. (c) `1/2kxs`D. (d) `1/2kx(s+x+s)`

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