The periodic time of a simple pendulum is 3.3 s. Now if the point of support of the pendulum starts moving along the vertically upward direction with a velocity $v = kt ( where k = 2.1 m/s^2 )$, then the new periodic time is……s. ${ Take g = 10 m/s^2 }$
Initial periodic time $T_1 = 2 \pi \sqrt { l \over g} …..(1) $ When pendulum moves along vertical direction, effective acceleration $ g_{eff} = g+a $ where ‘a’ inaccleration of pendulum. $now , a = { d \nu \over dt} = { d (kt) \over dt } = k = 2.1 ms^{-2} $ $ \therefore New periodic time T_2 = 2 \pi \sqrt { l \over g_{eff} } .....(2) $ $ \therefore { T_2 \over T_1 } = \sqrt { g \over g_{eff} }^1$