Swinging pendulum

Question

_{Because of air resistance, the length of each swing of a certain pendulum is 80% the length of the previous swing. If the first swing was 40 ft, find the total distance the pendulum will swing before coming to a rest.} 

Answer 1

To solve this problem, you calculate each swing until the swing length is zero, then add them all together.

 

Swing 1: 40ft,

Swing 2: 40ft*.8=32ft,

Swing 3: ...

And so on.

 

Then you add all of the swings together: 40ft+32ft+...