Answer:
Step-by-step explanation:
Given
Force=18lb
extension=8in
Using Hooke's law to get the spring constant(k)
F=ke
Then,
K=f/e
K=18/8
K=2.25lb/in
Work done by spring is given by
W=1/2Fe
Or W=1/2ke²
Then,
Work done in stretching the spring to 14in
W=1/2ke²
W=0.5×2.25×14²
W=220.5lbin
1 Inch-pounds Force to Joules = 0.113J
Then, to joules
W=0.133×220.5
W=29.33J