A spring with a force constant of 5.5 N/m has a relaxed length of 2.47 m. When a mass is attached to the end of the spring and allowed to come to rest, the vertical length of the spring is 3.78 m. Calculate the elastic potential energy stored in the spring.

The potential energy is 4.68 J

Explanation:

The force done by an spring is equal to:

F= K*x

where K is th force constant of the spring, and x is the change in the distance with respect to the relaxed lenght.

We know that the relaxed lenght is 2.47m and the force constant is 5.5N/m

Now, we know that after hanging a mass in the spring, the new lenght is 3.78m

So the displacement will be equal to: 3.78m - 2.47m = 1.31m

Now, the potential energy stored by a spring can be calculated as:

PE = (1/2)*k*x^2 = (5.5N/m*(1.31m)^2)/2 = 4.68 J