Two equal masses are attached to the two ends of a spring of spring constant k,
Two equal masses are attached to the two ends of a spring of spring constant k. The masses are pulled out symmetrically to stretch the spring by a length x over its natural length. The work done by the spring on each mass is
(a) 1/2kx2
(b) -1/2kx2
(c) 1/4kx2
(d) -1/4kx2.
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(d) -1/4kx2.
Explanation:-
The work done by the spring on both of the masses is equal to the potential energy stored in the spring. The potential energy stored in the spring = -½kx².
Since the masses are pulled out symmetrically, the work done by the string on each mass
=½(-½kx²) =-¼kx².
The negative sign is for the fact that displacement is opposite to the force.
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