Pendulum Swings

[Guest]

A pendulum is started swinging freely. Its first oscillation is through 30 degrees and each succeeding swing is 2/3 of the one before it. What is the total angle described before the pendulum stops?.

[shyamjayakannan]

sum = [tex]\displaystyle30 + 30\left(\frac{2}{3}\right)+30\left(\frac{2}{3}\right)^2+30\left(\frac{2}{3}\right)^3+...=\frac{30}{\displaystyle1-\frac{2}{3}}=\boxed{90}[/tex]