The amplitude of an oscillating mass on a spring decreases by 4% each cycle from an initial amplitude of 100mm. Calculate the amplitude after 20 cycles of oscillation.
You can start the problem by writing:
After 1st cycle, the amplitude A1 is
After 2nd cycle, the amplitude A2 is
After 3rd cycle, the amplitude A3 is
Till 20th cycle….
This problem is like “compound interest” problem in a reverse manner.
After one oscillation, the amplitude is 0.96*A
After two oscillations, the amplitude is (0.96^2)*A
After three oscillations, the amplitude is (0.96^3)*A
so what's the amplitude after 20 oscillations? No need to memorise a formula, just think about what's going on