can anyone help mi wif tis..?

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- Jun 21st 2006, 03:19 AM #1

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- Jun 21st 2006, 03:35 AM #2Originally Posted by
**xiaoz**Originally Posted by**some stupid assignment**

$\displaystyle T=\frac{2}{v}\left(\frac{Rd}{D}-r\right)$ divide both sides by $\displaystyle \frac{2}{v}$

$\displaystyle T\frac{v}{2}=\left(\frac{Rd}{D}-r\right)$ get rid of paranthesis..

$\displaystyle T\frac{v}{2}=\frac{Rd}{D}-r$ Add $\displaystyle r$ to both sides..

$\displaystyle T\frac{v}{2}+r=\frac{Rd}{D} $ multiply both sides by $\displaystyle D$

$\displaystyle DT\frac{v}{2}+Dr=Rd $ finally, divide both sides by $\displaystyle R$

$\displaystyle \frac{DT\frac{v}{2}+Dr}{R}=d $ simplify

$\displaystyle \frac{DTv}{2R}+\frac{Dr}{R}=d $ and that is what $\displaystyle d $ is.

Originally Posted by**some stupid assignment**

- Jun 21st 2006, 03:58 AM #3

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Hello, xiaoz1

Part (a) cn b solvd wif just algebra . . .

We hav: .$\displaystyle \frac{2}{v}\left(\frac{Rd}{D} - r\right)\;=\;T$

Mult by $\displaystyle v:\;\;2\left(\frac{Rd}{D} - r\right)\;=\;vT$

Div by $\displaystyle 2:\;\;\frac{Rd}{D} - r\;=\;\frac{1}{2}vT$

Add $\displaystyle r:\;\;\frac{Rd}{D}\;=\;\frac{1}{2}vT + r$

Mult by $\displaystyle D:\;\;Rd\;=\;D\left(\frac{1}{2}vT + r\right)$

Div by $\displaystyle R:\;\;d\;=\;\frac{D}{R}\left(\frac{1}{2}vT + r\right)$

an (b) is arithmetic, can b done wif yr calculator

- Jun 21st 2006, 04:17 AM #4
## Question 3

Originally Posted by**Quick Rocks :)**

That means the circumference of the wheel is 0.003125, and the diameter is of course the circumference divided by pi

$\displaystyle d=c\div \pi $ so I'm trusting you can find it from here.

- Jun 21st 2006, 04:25 AM #5

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- Jun 21st 2006, 08:26 AM #6Originally Posted by
**xiaoz**

$\displaystyle \frac{DTv}{2R}+\frac{Dr}{R}=\text{The Distance From the Moon to the Earth}$

$\displaystyle D=\text{The Distance Between the Sun and the Earth}$

$\displaystyle T=\text{The Time it Takes to Totally Eclipse the Sun}$

$\displaystyle v=\text{The Speed of the Moon}$

$\displaystyle R=\text{The Radius of the Sun}$

$\displaystyle r=\text{The Radius of the Moon}$

The book gave you all the numbers, so all you need to do is substitute them into the equation above.