Explanation:
Given that,
Initial length of simple pendulum, [tex]L_1=1\ m[/tex]
Initial time period, [tex]T_1=2\ s[/tex]
We need to find the length of the simple pendulum when the period is exactly 1 second.
[tex]T_2=1\ s[/tex]
We know that the time period of simple pendulum is given by :
[tex]T=2\pi \sqrt{\dfrac{L}{g}} \\\\T\propto \sqrt{L} \\\\\dfrac{T_1}{T_2}=\dfrac{L_1}{L_2}[/tex]
Put all values and find L₂
[tex]\dfrac{T_1}{T_2}=\sqrt{\dfrac{L_1}{L_2}}\\\\L_2=\dfrac{T_2^2L_1}{T_1^2}\\\\L_2=\dfrac{1^2\times 100\ cm}{2^2\ s}\\\\L_2=25\ cm[/tex]
So, the length of the pendulum with a period of exactly one second is 25 cm.