Question

What is the effective length of a second's pendulum for a place where g = 9.8 $m{s}^{-2}$? [Given: The time period of a seconds' pendulum = 2 s]

• A. 0.5 m
• B. 1 m
• C. 2 m
• D. 4 m

Answer 1

The correct option is B

1 m

Given: the time period of a seconds' pendulum = 2 s.

And we have,

$T^2=4{\pi }^2\frac{l}{g}$

$\Rightarrow 2^2=4{\pi }^2\frac{l}{9.8}$

$\Rightarrow l=\frac{9.8}{{3.14}^2}$

$\Rightarrow l=0.99m.$

Hence, the effective length of a second's pendulum, at a place where g = 9.8 $m{s}^{-2}$ is nearly 1 m.