Answer:
W = 8.575 foot-pounds
Step-by-step explanation:
The equation for work is: W = F*d
where F is force applied and d distance of the movement
from problem statement we have
d = 0,7 ft
We also know that the spring was stretched 0,4 ft when a force of 7 pounds was applied therefore
K the constant of the spring is
F = K*s
k = F/s ⇒ k = 7/0.4 ⇒ k = 17.5 pounds/feet
Now to move from original condition of the spring up to 0,7 feet we need a force of
F = k*s ⇒ F = 17,5 pounds/feet * 0.7 feet ⇒ F = 12.25 pounds
And finally the work
W = 12.25 * 0.7 = 8.575 foot-pounds
W = 8.575 foot-pounds
