Question

Given that $T=\frac{2\pi l}{\sqrt{l^2+g^2}}$, find the value of $T$ if $\pi =3.142$, $l=7.89$ and $g=9.81$.
(Give your answer correct to $3$ significant figures).

• A. $3.94$
• B. $394$
• C. $39.4$
• D. $4.39$

Answer 1

The correct option is A $3.94$

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

$\pi =3.142$

$l=7.89$

$g=9.81$

$T=\frac{2\times 3.142\times 7.89}{\sqrt{(7.89{)}^2+(9.81{)}^2}}$

$=\frac{49.5492}{\sqrt{158.4882}}$

$=\frac{49.5492}{12.589}$

$=3.935$

$=3.94$