1. The problem statement, all variables and given/known data A block of mass m = 4.30 kg slides along a horizontal table with speed v0 = 8.50 m/s. At x = 0 it hits a spring with spring constant k = 68.00 N/m and it also begins to experience a friction force. The coefficient of friction is given by μ = 0.200. How far did the spring compress when the block first momentarily comes to rest? m=4.30 kg vo=8.50m/s k=68.00N/m μ=.200 x=? 2. Relevant equations Kf-Ki=W K=1/2mv2 Fs=-kx Ffric=μNf W=Fd 3. The attempt at a solution First I found the work of the whole system (friction and spring forces) by using Kf-Ki=W. For the initial kinetic energy, I used K=1/2mv2=155J. For the final kinetic energy, I used 0, because I'm measuring the distance after the mass came to a stop. So, plugging the numbers into the Work equation, I simply get W=-155J I'm pretty sure I'm on the right track so far? Then, using W=Fd (just multiplying the forcexdistance because both vectors are in the same direction) I plugged in: W=(-kx+μNf)x I work it out to a quadratic by plugging the numbers in... -68x2+8.44366x+155=0 I solve then for x (using the quadratic root finder on my calculator, so I'm not screwing up the quadratic..), but both of the answers it gives me are incorrect.. What am I doing wrong? Help please!!