surface areas of human and sphere

[sculptor]

I seem to remember that an average human as surface area of 3300 sq inches.

Anyone have a different # ?

also is surface area of a sphere 4pi x radius squared?

rod(sculptor)

[fritchie]

sculptor - You're in the right ballpark for human area. An engineer's approach would be to take a cylinder of average human size, with surface area = pi x diameter x height. I took height = 5 feet, 7inches, or 67 inches; diameter = average of width (16) and thickness (10), and got 2734 square inches. With irregularities, a human of similar size would have greater surface.

The formula for a sphere is correct.

[MAD]

Hi There MADaboutART here in South Africa, we work with children using sculpture and painting to engage with kids on issues around HIV and AIDS and are in need of some help. the Kids at one of the art centres we have built are wanting to make a sphere for the centre piece of an exhibition on World AIDS Day and we need some simple ideas of hopw to contruct one. It is 2.5 m high and wire is proving too difficult

[sculptor]

Originally Posted by MAD

Hi There MADaboutART here in South Africa, we work with children using sculpture and painting to engage with kids on issues around HIV and AIDS and are in need of some help. the Kids at one of the art centres we have built are wanting to make a sphere for the centre piece of an exhibition on World AIDS Day and we need some simple ideas of hopw to contruct one. It is 2.5 m high and wire is proving too difficult

hi MAD

...... thoughts

you need a jig or template------do you have access to a bandsaw?
if so......make a circle cutting jig to radius 1.25 meters----my jigs are a plywood table that fits over the (supplied)bandsaw table with legs to support the out(center of radius) end. Set a pin proudly into the table in line with the front of the blade and at the desired radius. Then do a flat glue-up or find a wide enough piece of plywood, drill the hole for the proud end of the pin in the table and cut the arc. By cutting several and slotting them together you can creat a spherical template-jig over which you can weave wire.-----if you want, I'll post a picture of my 4 ft. one

or find a scrapyard with an old cylindrical tank of same diameter-----the ends should be 1/2 spheres----

or-----blow up a large balloon to apropriate diameter, and weave over this-----added excitement for youngsters

hope this helps

sculptor

[fritchie]

Hi, MAD, and congratulations on the project! Rod/sculptor’s suggestions give me the following ideas. If you have trouble with things like plywood, you might try drawing a partial circle on the ground by tying a string or chain of some sort to a central pin (the center), and then bending branches, vines, bamboo, or whatever is available to fit this partial circle or arc.

Get these arc pieces to stay in shape with wire, string, or whatever is necessary. I’m assuming that you probably are making a globe or “world”, and the inside will be covered. If the interior is to remain visible, you’ll have to be more careful with how you hold the arcs in proper shape.

You can make full circles by letting these arcs overlap and tying them with more wire or string. Make only a few full circles, maybe 3 or 4, and tie these together at north and south poles, and then use this rough framework to attach enough half-arcs to get the solidity you need for the full sphere.

You might also make a full circle for the “equator” to give the figure stability, and possibly some smaller “circles of latitude”. It also might be a good idea at a very early stage to attach a rigid, vertical pole of some sort to the ground or to a large, flat, moveable base as further support. Should the sphere be moveable?

Once you have a good frame of the sort above, you probably can cover it with vines, wire, or string to provide a close grid that can be completely covered with paper or cloth.

Let us know how this progresses!