# Can't find the right solution.

1. Mar 5, 2015

### governergrimm

1. The problem statement, all variables and given/known data
A spring of constant 19 N/cm is compressed a distance 8 cm by a 0.4 kg mass and then released on a frictionless surface. After it leaves the spring it skids over a frictional surface of length 1.9 m with coefficient of friction 0.14. Then, again on a frictionless surface, it compresses a second spring of constant 4 N/cm. The acceleration of gravity is 9.8 m/s 2 . How far must the second spring be compressed when the mass comes to rest? Answer in units of cm.

K1=19 N/m
x1=.08 m
m=.4 kg
Frictional surface = 1.9 m
μ=.14
K2=4 N/m
g=9.8

2. Relevant equations
Conservation of energy
work energy principle

N=mg
Ff=μmg

3. The attempt at a solution
http://www4c.wolframalpha.com/Calculate/MSP/MSP7167205289f8b7i74844000040h081bhh0e34g0i?MSPStoreType=image/gif&s=36&w=134.&h=35. [Broken]
solve for W
W=Fs-Ff
W=K1x1-μmg

x=sqrt((K1x^2+2W)/K2)

I end up with

http://www5a.wolframalpha.com/Calculate/MSP/MSP17542240fg7bd54i8f4500000cff0b06i93i7dc9?MSPStoreType=image/gif&s=19&w=191.&h=47. [Broken]

Last edited by a moderator: May 7, 2017
2. Mar 5, 2015

### billy_joule

Check the consistency of your units.