What is the Damping Constant for a Hard Boiled Egg on a Spring?

[jghlee]

Homework Statement

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.

Homework Equations

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

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!

 

[Redbelly98]

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.

 

[jghlee]

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.

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?

 

[Redbelly98]

Check it out:

http://hyperphysics.phy-astr.gsu.edu/HBASE/oscda.html#c2
http://hyperphysics.phy-astr.gsu.edu/HBASE/oscda.html#c3