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Expert: - 10/16/2010


Question
Pipe is 2.5cm thick, 2m in height and 40cm in diameter

Volume of metal using (pi x r1 x r1 x h)- (pi x r2 x r2 x h) is 58,875 cm cubed.

If you imagine pipe rolled out into rectangular shape you can use l x b x h = 2 x pi x r1 x 2.5 x 200 and the anwer is 62,800 cm cubed.

Why are the answers different ?

Thks

Akan

Answer
It is different because the radius on the insides of the pipe is smaller than the radius on the outside the pipe.

This means if it was rolled out into a flat sheet, it would not form a sheet that had a edge that was straight up and down.

If the sheet were laid out with the outside on the bottom, it would be slightly wider on the bottom if it could be laid flat at all.

The width on top would have the with of the inside circumference
and the width on the bottom would have the width of the outside circumference.

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