Rearranging Young's Modulus Equation for Force: Help Needed!

[tommowg]

Homework Statement

Hi all I'm new and wondering if you could help me rearrange this equation for a Young Modulus question:

Homework Equations

Equation for Young Modulus is E = F*L/A*ΔL

* is multiplied
/ is divide

How can I make F the subject of this equation?

The Attempt at a Solution

I have attempted but not very good at rearranging, I managed to get F = E*L/A*ΔL
but that is wrong I think.

All help would be really appreciated, thanks.

Tom

 

[Mentallic]

If you have $$a*b=c$$ then to make a the subject, you divide both sides by b to give $$\frac{a*b}{b}=\frac{c}{b}$$ and the b's cancel on the left side, so you have $$a=\frac{c}{b}$$

If you have $$\frac{a}{b}=c$$ then multiply both sides by b to make a the subject, giving $$a=b*c$$

All you have to do is apply these two ideas to your problem, and you should be set.

 

[tommowg]

I've used your idea to come up with:

F = E/L*A*ΔL

Is this right?

Thanks.

 

[Mark44]

Homework Statement

Hi all I'm new and wondering if you could help me rearrange this equation for a Young Modulus question:

Homework Equations

Equation for Young Modulus is E = F*L/A*ΔL

The equation for Young's Modulus is incorrect. The correct version is:
$$E = \frac{F*L}{A*\Delta L}$$

I don't doubt that this is what you meant, but when you write a fraction on a single line, you need parentheses to indicate what's in the numerator and what's in the denominator. A better way to write this equation would be E = (F*L)/(A*ΔL).

As you wrote it, the expression on the right side would be interpreted as
$$F \frac{L}{A} \Delta L$$

* is multiplied
/ is divide

How can I make F the subject of this equation?

The Attempt at a Solution

I have attempted but not very good at rearranging, I managed to get F = E*L/A*ΔL
but that is wrong I think.

All help would be really appreciated, thanks.

Tom

To solve for F, multiply both sides of the equation by the reciprocal of the coefficient of F. The coefficient of F is L/(AΔL).

 

[Mentallic]

I've used your idea to come up with:

F = E/L*A*ΔL

Is this right?

Thanks.

Depends, use parenthesis as Mark44 has suggested so I know what your answer actually is.