Amy pulls a spring with a spring constant k = 100 stretching it from its rest length of 0.10 m to 0.2

Elastic potential energy  E = 0.5 J

Explanation:

Let us assume we have to find the elastic potential energy stored in the spring.

Given: k = 100

change in the length of the spring x = 0.2-0.1 = 0.1 m

Elastic potential energy

E =

plugging the values we get

Hence, Elastic potential energy  E = 0.5 J

because if the tool that you are using is not balanced it there would be false mass.