How Do You Calculate the Damping Coefficient of a Pendulum in Water?

[math111]

I am giving M=1kg, L=1.0m, T(period) = 2.02sec. I need to find C

The pendulum is in water.

The eq of motion is double-dot-theta+(c/m)single-dot-theta+(g/l)theta = 0

I was doing some research and found this half life formula...T(1/2) = LN(2)/ Lamda. I am not sure where to go from here...

I know Wn = sqrt(g/L)...

 

[tiny-tim]

I am giving M=1kg, L=1.0m, T(period) = 2.02sec. I need to find C

The pendulum is in water.

The eq of motion is θ'' + (c/m)θ' + (g/l)θ = 0

I was doing some research and found this half life formula...T(1/2) = LN(2)/λ. I am not sure where to go from here...

I know Wn = sqrt(g/L)...

Hi math111!

(have a theta: θ and a lamda: λ and use ' instead of dot )

hmm … I'm don't think that T(1/2) is the same T that you were given.

It is not a good idea to trawl the web looking for an equation that might fit.

Hint: do you know any method of solving θ'' + (c/m)θ' + (g/l)θ = 0 ? ​