F is inversely proportional to $\sqrt{g}$ $sqrtg$ when f=15, g=144. How do you work out g when f=90?

Question

2539 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-11-24T03:35:07

$g = 4$ $g=4$

As $f$ $f$ is inversely proportional to $\sqrt{g}$ $sqrtg$ ,

it means $f \propto \frac{1}{\sqrt{g}}$ $fprop1/sqrtg$

i.e. $f = \frac{k}{\sqrt{g}}$ $f=k/sqrtg$ , where $k$ $k$ is a constant

When $f = 15$ $f=15$ , $g = 144$ $g=144$

Hence $15 = \frac{k}{\sqrt{144}} = \frac{k}{12}$ $15=k/sqrt144=k/12$

and $k = 12 \times 15 = 180$ $k=12xx15=180$

Hence equation is $f = \frac{180}{\sqrt{g}}$ $f=180/sqrtg$ and when $f = 90$ $f=90$ ,

we have $90 = \frac{180}{\sqrt{g}}$ $90=180/sqrtg$

or $\sqrt{g} = \frac{180}{90} = 2$ $sqrtg=180/90=2$

and $g = 4$ $g=4$

F is inversely proportional to √gsqrtg when f=15, g=144. How do you work out g when f=90?