# Damped Oscillations Problem

1. May 31, 2009

### jghlee

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

A 45.0-g hard boiled egg moves on the end of a spring with a force constant k = 2.50 N/m. Its initial displacement is 0.500 m. A damping force Fx = -bvx acts on the egg, and the amplitude of the motion decreases to 0.300 m in 4.0 s. Calculate the magnitude of the damping constant b.

2. Relevant equations

(1/2)m(v^2) + (1/2)k(x^2) - bv = (1/2)m(A^2)

3. The attempt at a solution

So basically I thought you could solve this question by using the above equation. But I'm finding some difficulty in finding the correct value for v (from bv). Also I'm not sure on how to incorporate the fact that the amplitudes change in 4 seconds into this equation. Any help will be appreciated!

2. May 31, 2009

### Redbelly98

Staff Emeritus
That equation is wrong. Since bv is a force, no way can it be added or subtracted from these other terms which are energies.

Usually a problem like this is solved by looking in your textbook for the equation of a damped oscillator.

3. Jun 3, 2009

### jghlee

I'm still having trouble doing this problem. I don't seem to find any equation where I can incorporate the different values given in the question.

Can anybody help me?

4. Jun 4, 2009

### Redbelly98

Staff Emeritus