Stuck on simple Maths Question

SilverKrest

Completely stuck on this question. Does anyone know the steps. Any help appreciated.

Find an expression for b given:
0.0505=f[(0.09/b^2)/(2*9.81)]

The answer is: b=0.38f^(1/5)

Just cant reach this answer

Yakuza

Does f[] describe a function or is f just multiplied by the term in square braces?[] If f is a function, please add f[x] to the problem.
Can you use Latex or upload a scan of the original question, as your notation isn't very clear.

At a wild guess, is it some form of applied maths or mechanics question (assuming the 9.81 refers to g, the acceleration due to gravity)?

SilverKrest

The f is multiplied by the bracket. Yes it is gravity. And apologies but I'm not allowed to upload images as I've too few posts on this

SilverKrest

Have the correct format now.
Here is question: http://www.hostmath.com/Show.aspx?Code=0.0505=f(\frac{\frac{0.09}{b^{2}}}{2\times9.81})

And here is answer: http://www.hostmath.com/Show.aspx?Code=b=0.38f

SilverKrest

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Edit: the f should be also to the power of a fifth (in the answer link)

dlouth15

Here are some suggested steps.

1. Simplify the right hand side so you don't have two divisions.

2. Rearrange so that the [latex]b^2[/latex] is on the left hand side and the 0.0505 is on the RHS. Basically swap the two.

3. Take the sqrt of both sides so you have b on the LHS and a an expression involving numbers times [latex]f^{1/2}[/latex] on the RHS.

Here is the first step:

[latex]\displaystyle{0.0505 = f\left(\frac{\left(\frac{0.09}{b^{2}}\right)}{2\left(9.81\right)}\right)=\frac{0.09}{2\left(9.81\right)b^{2}}\times f[/latex]

Btw, I don't get [latex] b=0.38f^{1/5}[/latex]. I don't think the answer is correct. Are you sure it is [latex]b^2[/latex] in the question.