Answer:
5cm
Explanation:
Let's assume that the object started from its mean position. Then it went to its extreme position followed by returning to its mean position. Then again, it follows the same cycle in the opposite direction and completes one vibration.
which is 4 Amplitudes.
Let's take these 4 amplitudes as 4A, then,
4A=20cm
A=20/4=5cm
Therefore, the amplitude is 5cm.
