# Simple harmonic motion problem

1. Dec 4, 2012

### DLH112

1. The problem statement, all variables and given/known data
This is a 3 part problem and I've successfully solved the first 2 parts, but I don't know what I did wrong in the third part.

1) mass of 346 g on a spring with constant 26.8 N/m on a horizontal + frictionless surface.
Amplitude is 6.7 cm. In part 1 i found the total energy to be 0.0601526 J. and in part 2 i found the max speed to be 0.58966337 m/s.

part 3 is "What is the magnitude of the velocity of the mass when the displacement is equal to 3.6 cm? answer in m/s"
2. Relevant equations
E = KE + PE , 1/2KA^2 = 1/2kx^2 + 1/2mv^2

3. The attempt at a solution
using the energy from part 1 as E...
0.0601526 = (0.5)(26.8)(0.036)^2 + (0.5)(0.346)v^2
0.061526 = 0.0185328 + (0.5) (0.346)v^2
0.0416198 = (0.5)(0.346)v^2
0.2405768786 = v^2
0.4904863694 m/s = V .... is apparently wrong

2. Dec 4, 2012

### Staff: Mentor

Double check the highlighted term.

3. Dec 4, 2012

### DLH112

ah thank you. i was accidentally using 28.6 instead of 26.8.