Answer:
14.04 J
Step-by-step explanation:
First, we need to calculate the magnitude of the force, so by Hooke's law, it is equal to
F = kx
Where k is the spring constant and x is the stretch. Since it goes form 0.3 m to 0.9 m, the value of x is:
x = 0.9 m - 0.3 m
x = 0.6 m
Then, replacing k = 39 N/m and x = 0.6 m, we get that the force is
F = (39 N/m)(0.6 m)
F = 23.4 N
Now, the work done is equal to the force times the distance, so
W = Fx
W = (23.4 N)(0.6 m)
W = 14.04 J
Therefore, the work done by the force was 14.04 J