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CaptainSFS
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Homework Statement
A spring is stretched a distance of Dx = 40 cm beyond its relaxed length. Attached to the end of the spring is an block of mass m = 8 kg, which rests on a horizontal frictionless surface. A force of magnitude 20 N is required to hold the block at this position. The force is then removed.
Homework Equations
W=Fd
KE=(.5)(m)(v)^2
KE(final) - KE(initial) = W
The Attempt at a Solution
I first found work, which I calculated (20N)(.4m) = 8 J
Then I plugged it into: 8 J = (.5)(8kg)(0m/s) - (.5)(8kg)(v)^2
8 = 0 - 4(v)^2
I end up with -(sqrt(2)) or +(sqrt(2)), but neither of those are correct. Any ideas with what I am doing wrong?