# Homework Help: Confirm my answers on Oscillating Springs?

1. Apr 24, 2010

### vtmvick7

confirm my answers on Oscillating Springs??

Can anyone confirm or adjust my answers for problems 12 and 14? Also can someone help me start on problem 13.. Thanks guys I really appreciate the help

1. The problem statement, all variables and given/known data

012
Find the speed of the block when it is 2.5 cm
from the equilibrium position.

013
Find its acceleration at 2.5 cm from the equilibrium position.

014
Find the time it takes the block to move from
x = 0 to x = 2.5 cm.

2. Relevant equations
M= 0.7kg
k= 14.7 N/m
A= 5cm
T= 1.37s

3. The attempt at a solution

t= (1/4.58 rads/s) cos^-1 (2.5cm/5cm) = 13.09s??
do I convert it to meters??

#12: E=1/2mv^2 + 1/2kx^2 = 1/2ka^2
1/2(.7)v^2 + 1/2(14.7)(.025m)^2 = 1/2(14.7)(.05m)^2
.35v^2=.0137
v=0.1984m/s
I changed the cm to m, I should have done this right??

2. Apr 24, 2010

### vtmvick7

Re: confirm my answers on Oscillating Springs??

I think I solved #13.. would I use the equation

a = -w^2 * x???

3. Apr 24, 2010

### Bearbull24.5

Re: confirm my answers on Oscillating Springs??

I think that works but that is the equation for maximum acceleration. This means that equation might not always work for a problem such as this. Is acceleration always at maximum when it is half the distance from the equilibrium? (I don't know the answer to this)

I did this problem a different way.