# Mechanics Geometry

• Jun 1st 2008, 08:31 AM
Simplicity
Mechanics Geometry
Question:
http://i148.photobucket.com/albums/s...csGeometry.jpg

http://i148.photobucket.com/albums/s...sGeometryA.jpg

My Problem:
I don't understand what they have done in the mark scheme where I have put a red box around the part that I don't understand. Please help. Thanks in advance.
• Jun 1st 2008, 08:44 AM
bobak
They are using a standard result, The center of mass of a uniform solid right circular cone is distance $\frac{h}{4}$ from the base (where h is the height of it.)

Bobak
• Jun 1st 2008, 08:54 AM
bobak
I attached the formula you will be given in your M3 exam if your interested in it.

Bobak
• Jun 1st 2008, 08:54 AM
Simplicity
...And what did they do to get $\tan \theta$? What rule is it that says external angle equals that of the internal?

http://i148.photobucket.com/albums/s...ryExtended.jpg
• Jun 1st 2008, 08:57 AM
bobak
Quote:

Originally Posted by Air
...And what did they do to get $\tan \theta$? What rule is it that says external angle equals that of the internal?

http://i148.photobucket.com/albums/s...ryExtended.jpg

the tangent is just a given, they didn't work it out they defined it to make working out the height a bit more interesting.

Bobak