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A catapult with a spring constant of 1.0 104 newtons per meter is required to launch an airplane from the deck of an aircraft carrier. The plane is released when it has been displaced 0.50 meter from its equilibrium position by the catapult. What is the energy acquired by the airplane from the catapult during takeoff
0.50 m is presumably how far the spring is pulled back, not the displacement when the airplane leaves the catapult.
In this case, the energy acquired is (1/2) k X^2
k = 1.0*10^4 N/m
X = -.50 m
The answer will be in Joules