1. This is sorely to reduce error as larger amplitude will increase angle of deflection thus creating much space for blunders.
2. Conditions;
* The object must exhibit periodic motion that is to and fro motion about it's mean position.
* The restoring force must be directly proportional to the extension and must act opposite the direction of the motion.
* The acceleration must be directly proportional to the extension and act opposite the direction about the mean position.
3. It's known,
[tex]t = 2\pi \sqrt{ \frac{m}{k} } [/tex]
from 1st eqn, when mass is doubled then m will be 2m
and,
[tex] {t }^{2} = 4 {\pi}^{2} ( \frac{m}{k} )[/tex]
thus, 2m will increase T by factor of √2.