This is incorrect. The problem with the answer starts here:
"Also, the point will lie on the plane which divides the top and bottom such that the volumes are equal."
This would only be true if the cg's for both halves were the same distance from that plane. But they aren't.
The solution is pi*int( t*(a2-t2)dt,0 to a)/(volume of hemisphere=2/3*pi*a3)
pi's cancel.
cg at ([a2t2/2-t4/4],0,a)/(2/3*a3)
= (a4/4)/(2/3*a3)
= 3/8 a from the base.
------
Whoops! I did not mean to wipe out the original answer, and am a bit surprised that I apparently have the power to do that. Sorry!
The original answer found the distance from the base to a plane that divided the hemisphere into two equal halves, at t= ~0.347a. That might be useful information but is not the cg.
A steradian is the solid angle subtended at the centre of a sphere by radius r by a portion of the surface of the sphere which has area r2.
hemisphere
A hemisphere
The radius of a circle is constant regardless of where it is, so if the radius of the circle at a cross section is 8 inches, then the radius of the circle is 8 inches. However, if you mean you know the length of the chord 8 inches from the centre of the circle, then you can create an isosceles triangle by joining the ends of the chord to the centre of the circle. If you now drop a perpendicular from the centre of the circle where the radii drawn in meet, it will bisect the chord and form two congruent right triangles which have one leg 8 inches long, one leg half the length of the chord and a hypotenuse the radius of the circle. You can now use Pythagoras to find the unknown radius from the two lengths you do know: radius² = (8 in²) + (chord_length/2)² There is more to this problem which you have not stated as it is very unusual to use the phrase "CROSS-SECTION 8 inches from the centre OF A CIRCLE"; cross-sections are used with 3 dimensional objects whereas a circle is a 2 dimensional object. I would guess that you have some solid (say a sphere) where a circular cross-section has been created 8 inches from the centre of the object and you want to know its radius. In this case you can use Pythagoras as above: radius_object² = (8 in)² + (radius_circle)² by considering a plane that slices through the centre of the original object and bisects the circle created in the cross-section.
A cylinder or a cone. Or a hemisphere.
Take an elemental mass on the solid hemisphere. Let the mass be in thin form of discs. The centre of mass lies at the centre of the disc. Integrate the whole function to get the c.o.m.
solid angle is the ratio of the intercepted area dA of the spherical surface , described about the apex O as the centre ,to square of its radius r
It is in square units: (2*pi*radius2)+(pi*radius2)
A steradian is the solid angle subtended at the centre of a sphere by radius r by a portion of the surface of the sphere which has area r2.
The centre of the earth is solid iron, however the centre of the earths gravitational pull changes, due to the movement of the moon, which has an effect on the earths gravity.
The upward thrust which the surrounding fluid exerts on an object is referred to as the force of buoyancy. This thrust acts through the centroid of the displaced volume, referred to as the centre of buoyancy. The centre of buoyancy is not the same as the centre of gravity which relates to the distribution of weight within the object. If the object is a solid with a uniform density exactly the same as water and the body is immersed in water the force of buoyancy will be exactly equal to the weight and the centre of buoyancy will be the same as the centre of gravity. The object will be in equilibrium with the surrounding fluid.
The centre is called the Inner Core and is solid.
One.
hemisphere
gravity affects everything with mass
The heavier mass will be nearest to the center of mass. The concept behind this is related to the one that explains the center of gravity. The center of mass and the center of gravity are the same.
Composite numbers can be written as product of prime factors.