Time period of a pendulum is given by --
[tex]T=\text{ 2}\pi\sqrt[\placeholder{⬚}]{\frac{l}{g+a}};[/tex]According to problem
When it is at rest, it oscillates with a period of 1 second. When it is accelerating in an elevator it oscillates with a period of 2 seconds.
From above equation we can conclude that time period of pendulum depends on acceleration and it is inversely proportional .
So its is a Pendulum.
final answer is :- pendulum
