Answer:
0.248 m
Step-by-step explanation:
The period of a simple pendulum is given by
![T=2\pi \sqrt{(L)/(g)}](https://img.qammunity.org/2020/formulas/physics/middle-school/y1n88s7n9sfdh50a931nnr27hx16gzobsz.png)
where
L is the length of the pendulum
g is the acceleration of gravity
The pendulum in the problem passes its lowest point twice every second: this means: this means that it makes one complete oscillation in one second, so its period is 1 second:
T = 1 s
And using
![g=9.8 m/s^2](https://img.qammunity.org/2020/formulas/physics/high-school/pzbgdnh5dnauj7cfcpu92d9km30p4mlye9.png)
We can rearrange the equation above to find L, the length of the pendulum:
![L=(T^2 g)/(4\pi^2)=(1^2(9.8))/(4\pi^2)=0.248 m](https://img.qammunity.org/2020/formulas/physics/middle-school/bjk1h8qgltcqa8ydx7u3w1jfhg1r3mdxvk.png)