Question

A block is attached to the end of an ideal spring and moved from coordinate xi to coordinate Xf The relaxed<br />position is at x = 0. The work done by spring is positive if<br />(1) xi= 2 cm and xf = 4 cm<br />(2) xi = -2 cm and xf = 4 cm<br />(3) xi = - 4 cm and xf = -2 cm<br />(4) xi = 4 cm and xf = - 2 cm<br />i denotes initial and f denotes final<br />​

Answer 1

Answer:

Explanation:

Keeping in view that; a block is attached to the end of an ideal spring & moved from coordinate Xi to xf the relaxed position is at x=0.

The work done by spring is positive if xi =−4cm and xf =−2cm

This is because the spring is relaxed at x=0 , therefore in all options apart from "xi =−4cm and xf =−2cm " the spring is either compressed or stretched and is moving towards a more strained position respectively. This shows that work is done on the spring or work done by the spring is negative.

Yet when, xi =−4cm and xf =−2cm

the spring is going from stretched/compressed state to relaxed therefore work done by spring is positive.