A pillar 2m tall stands on a square base, 20cm on a side. The peculiar thing about this pillar is that its top, which is parallel to the base, is an equilateral triangle 16cm on a side.

The four edges running the length of the pillar are linear. Two of these edges meet at one corner of the triangle, and the edge of the triangle opposite this vertex is parallel to two edges of the square. All horizontal cross sections have straight edges.

If the pillar is made of basalt (density = 2.8 g/cm^3), what is its total mass?

(this may be the same as previous, I have not yet looked)
the volume of the pillar would be the average of two pillars (one with the triangle base, one with the square base)
V of pillar with triangle base = .5*16*13.85*200 = .5bhd = 22160
V of pillar with square base = 20*20*200 = 80000
The mean of the two would be = (80000+22160)/2 = 51080 cm^3 * 2.8g/cm^3 = 143024g

Posted by Hank on 2003-04-15 04:22:19