1. The problem statement, all variables and given/known data 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.) 2. Relevant equations -Fspring = Fapplied Fspring = -kx -Wspring = Fapplied Wspring = 0.5k(x12 - x22) 3. 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.