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## Homework Statement

I have a ball of 20 kg describing a damped harmonic movement, ie,

m*∂^2(x)+R*∂x+K*x=0,

with m=mass, R=resistance, K=spring constant.

The initial position is x(0)=1, the initial velocity is v(0)=0.

Knowing that v(1)=0.5, v(2)=0.3, I have to calculate K and R.

**2. The attempt at a solution**

I know that if R^2 < 4*m*K, the solution with x(0)=1 and v(0)=0 is such that:

∂x(t)=exp(-R/(2*m)*t)*[-(R/(2*m)^2)/(√[K/m-(R/(2*m))^2])-√[K/m-(R/(2*m))^2]]*sin(√[K/m-(R/(2*m))^2]*t), and I solve the sistem of equations, but it has to be a simpler way to do it (and also I don't use the mass of the ball)

Thanks!