UPSEE 2019 Solved Paper

According to the question, we draw the following situationAs, the point of suspension is moving upward according to the relation
y=λt2

dy

dt

=2λt
Further,

d2y

dt2

=2λ= upward acceleration a
Here, 2λ is the acceleration of point of suspension. The bob experiences a downward reaction force.
Hence, the new time period
T′=2π√

L

g+a

.......(i)
Whereas the time period of simple pendulum,
T=2π√

L

g

......(ii)
By comparing Eqs. (i) and (ii), we get
T′<T
Hence, the new time period is less than T.