Answer:
3.73 m/s^2
Step-by-step explanation:
The period of a simple pendulum is given by
(1)
where
L is the length of the pendulum
g is the gravitational acceleration on the planet
The pendulum in the problem has length
L = 0.640 m
and makes 10 oscillations in 26.0 s; it means that its frequency is

And so its period is

So now we can solve equation (1) using L=0.640 m and T=2.6 s, so we can find the value of g on the planet:
