Answer:
Explanation:
For simple pendulum the formula is
[tex]T=2\pi\sqrt{\frac{l}{g} }[/tex]
Where T is time period , l is length and g is acceleration due to gravity .
[tex]\frac{1}{n} =2\pi\sqrt{\frac{l}{g} }[/tex]
n is frequency
Putting the values
[tex]\frac{1}{.4} =2\pi\sqrt{\frac{l}{10} }[/tex]
[tex]\frac{l}{10} = .1584[/tex]
l = 1.584 m
