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Senrai
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Homework Statement
One end of a spring is attached to a block and the other is attached to a wall. The spring has no mass and the block lies atop a frictionless surface. The equilibrium point of the system is at x = 0 cm. A force of 80N must be applied to the block to hold it stationary at x = -2 cm. From this position, the block is slowly moved until the applied force has done 4J of work on the spring-block system; the block is then again stationary. What is the block's position? (There are two answers.)
Homework Equations
-Fspring = Fapplied
Fspring = -kx
-Wspring = Fapplied
Wspring = 0.5k(x12 - x22)
The Attempt at a Solution
I first solved to get the spring's spring constant, k.
-Fspring = Fapplied
-Fspring = 80N
Fspring = -80N
Fspring = -kx
-80N = -k(-0.02m)
-80N/-(-0.02m) = k
-4000N/m = k
I don't think there can be negative spring constants, so I changed this to 4000N/m.
I then solved to get the block's final position.
-Wspring = Fapplied
-Wspring = 4J
Wspring = -4J
Wspring = 0.5k(x12 - x22)
-4J = 0.5(4000N/m)((-0.02m)2 - x22)
When I worked that equation out, I came up with a final position of +- 0.04899m, which was incorrect.
I've been at this for hours and can't solve it. Any help would be greatly appreciated.
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