Question

A block of mass m is pushed up against a spring with spring constant k until the spring has been compressed a distance x from equilibrium. what is the work done on the block by the spring.
A. W=kx^2
B.W=-kx^2
C.W=0
D. None of these

Answer 1

Answer:d

Explanation:

Spring is compressed to a distance of x from its equilibrium position

Work done by block on the spring is equal to change in elastic potential energy

i.e. Work done by block $W=\frac{1}{2}kx^2$

therefore spring will also done an equal opposite amount of work on the block in the absence of external force

Thus work done by spring on the block $W=-\frac{1}{2}kx^2$

Thus option d is correct