Question

In the figure, we must apply a force of magnitude 82.0 N to hold the block stationary at x = -2.00 cm. From that position, we then slowly move the block so that our force does +7.00 J of work on the spring–block system; the block is then again stationary. What are the block's positions? ((a) positive and (b) negative)

Answer 1

Force applied to the block to keep it stationary is ,

Initial position of block is

Spring constant

Now the external force does work on block to move it to a new position

Work doen by external force is

Work done by all the forces = Change in kinetic energy of block

( the block is at rest initially and finally , so )

Block's positions are:

a)

b)