Simple Pendulum
' ' and ' ' are fixed points in same plane and mass ' ' is tied by string as shown in figure. If the mass is displaced slightly out of this plane and released, it will oscillate with time period gravitational acceleration)

Show answer and solution
Answer: (c)
- Displaced out of the plane, the mass swings about the line .
- Effective length = distance of from : .
- So the answer is (c).