REASK - sorty tricky math question?

Question

The tunnel under the english channel that connects england and frances is the worlds longest. There are actutally three seperate tunnels built side by side. Each is a half-cylinder that is 50,000 meters long and 4 meters high (think of a long pipe cut in half the lng way). How many cubic meters of dirt had to be removed to build this tunnel?

Answer 1

This is not tricky at all. The volume is 1-1/2 cylinders of "height" 50,000 meters and radius 4 meters.

The formula for the volume of a cylinder is

V = pi * r^2 * h

Answer 2

If R is the radius of the "complete" cylinder cross section
and L is the length of the cylinder
the the volume v of the "complete" cylinder would be:

v = PI*R^2*L

so the volume of half a cylnder is (1/2)PI*R^2*L

and 3 of them make (3/2)PI*R^2*L
= (1.5)(3.14)(4.0)^2(50000) = 3.77 * 10^6 meters^3

Answer 3

formula for the area of a circle:
(pi)r^(2)

Formula for the volume of a cylinder:
length*(pi)r^(2)

Volume of one half cylinder 50,000 m long and 4 meters high:
[(50,000)(pi)4^(2)]/2

Volume for 3 such tunnels:
3*{[(50,000)(pi)4^(2)]/2}

Answer 4

use the formula for volume of a cylinder

Answer 5

i didn't know the number but it's equals to the area of that cylinder