Answer:
Step-by-step explanation:
First of all, well calculate the spring constant k
K = 2Ei/x^2
Where Ei = initial work required
x = initial stretch length
k = 2×7/0.017^2 = 48443J/m^2
Now work done in stretching it to 5.3cm (1.7 + 3.6) or 0.053m
EF = kx^2/2
48443 × 0.053^2/2 = 68J
Work done in stretching additional 3.6cm is equal to
68J-7J = 61J