Answer:
74.958 lb-in
Step-by-step explanation:
We are given that
Natural length of spring=l=6 in
After stretching, the length of spring=8.3 in
Weight=W=9 lb
Extension in the sprig=8.3-6=2.3 in
By hook's law
[tex]F==W=kx[/tex]
Using the formula
[tex]9=k(2.3)[/tex]
[tex]k=\frac{9}{2.3}=3.9 lb/in[/tex]
Extension in the spring when the length of spring after stretching to 12.2 in=12.2-6=6.2 in
Work done, W=[tex]\int_{0}^{6.2}3.9xdx[/tex]
[tex]W=[\frac{3.9x^2}{2}]^{6.2}_{0}[/tex]
[tex]W=3.9\times \frac{(6.2)^2}{2}[/tex]
[tex]W=74.958 lb-in[/tex]
