A cylindrical piece of iron pipe is shown below. The wall of the pipe is 0.75 inch thick, and the pipe is open at both ends. What is the approximate inside volume of the pipe?

Question

anonymous · Answer

attachment

anonymous · Answer

pi*r2*h right?

anonymous · Answer

thats right use this formula
Volume of a cylinder with radius r and h for height is
$$\pi r^2 h$$

anonymous · Answer

so pi*4squared*12

anonymous · Answer

but what would the smaller one be?

anonymous · Answer

i have no clue to be honest. this is confusing to me

jim_thompson5910 · Answer

Here's a look at the top (think of it as you're looking down the pipe)

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jim_thompson5910 · Answer

|dw:1341439859180:dw|

jim_thompson5910 · Answer

Basically the outer circle has a radius of 4. 

The tube has a thickness of 0.75

The inner circle has a radius of x, which means that x+0.75 = 4

jim_thompson5910 · Answer

Hopefully that drawing makes sense

anonymous · Answer

so x is 3.25

jim_thompson5910 · Answer

you got it

anonymous · Answer

and i have to have to subtract inner cylinders volume from outer cylinders volume right?

jim_thompson5910 · Answer

No you only have to find the volume of the space inside the pipe (ie where open air is)

jim_thompson5910 · Answer

So you only need to find the volume of the inner cylinder

anonymous · Answer

oh right! okay i think i got this now!

jim_thompson5910 · Answer

that's great

anonymous · Answer

thanks so much! :)

jim_thompson5910 · Answer

yw