Answer:
g = 11.2 m/s²
Step-by-step explanation:
First, we will calculate the time period of the pendulum:

where,
T = Time period = ?
t = time taken = 135 s
n = no. of swings in given time = 98
Therefore,

T = 1.38 s
Now, we utilize the second formula for the time period of the simple pendulum, given as follows:

where,
l = length of pendulum = 54 cm = 0.54 m
g = acceleration due to gravity on the planet = ?
Therefore,

g = 11.2 m/s²