The smooth 2-kg collar is released at A and moves to the right by 0.8 m (reaching position C). The spring has an unstrected length of 0.3 m. What is the work done by the spring on the collar from A to C?

4.9 J

Explanation:

From hook's law,

The work done in stretching a spring is given as,

E = 1/2F*e ... Equation 1

Where E = Wok done, F = force on the spring, e = extension.

Note: from the question, The force on the spring is the weight of the collar on the spring, Therefore,

F = W.

Then,

E = 1/2W*e ... Equation 2

Given: W = mg = 2*9.8 = 19.6 N, e = 0.8-0.3 = 0.5 m

Substitute into equation 2

E = 1/2 (19.6) (0.5)

E = 4.9 J.

Hence the work done by the collar = 4.9 J