The ball is hung on a thread with a length of l = 20 cm. Another three balls are hung on threads with lengths l = 10cm, l = 20cm and l = 30cm.1. Determine the natural frequencies of mathematical pendulums2. We deflect the first ball with length l = 20cm from its equilibrium position and let it vibrate freely. Compare the amplitudes at which the balls begin to vibrate. When the vibration of which ball is resonance observed (g = 10m / s²)