calculating volume?

Question

Which is more accurate in calculating volume or a metal object ( a solid object in general):

a.) using water displacement
b.) by dimensions then using the formula V = (r^2) (3.14) (h)

Please provide your comment with some explanation to explain why your chosen method in calculating density is more accurate. Thanks.

oops. I meant to say volume instead of density in the last paragraph.

Answer 1

well by using (pi) in your 2nd equation I assume it is a round object, you didn't say: just solid object. I think the 2nd method will be more accurate, because polarity of water causes it to make a curve at the edges, making readings not 100% accurate. Best thing is to try both methods for a known volume and then compare the results. What do you need density for or am I missing something here? good luck!

Answer 2

First, you equation in b.) only applies to cylinders. Any other shape geometric shape ( a cube, a sphere, etc) will need a different formula.

Second, for non-geometric shapes, say, a metal claw-hammer-head, it is almost impossible to develop an appropriate equation. Imagine trying to algebraically trying to describe a random metal "splat" or a metal snowflake. The famous story where archemides supposedly developed the water displacement technique involved getting the density for an elaborately shaped crown without deforming it.

Third, and finally, neither technique is inherantly more accurate. It depends on the accuracy of your method. What are you using to measure the amount of water displaced? What kind of device to measure the dimensions?

So, water displacement works in most cases, dimensional measuring is not practical much of the time. Accuracy depends on technique.

Answer 3

water displacement, since that formula does not accually calculate the volume of an "odd" shaped object.

also volume is tottally different then density. volume is the space something takes up, and density is how much of it is there.

water could get into all the little crevicies etc of an object therefore highly accurate in measureing volume. Thats my 2 cents anyway lol.

Answer 4

water displacement is more accurate because it would be impossible to exactly determine the dimensions of an irregular object. no matter what shape the object is in water displacement will be accurate

Answer 5

I think this site will help...
http://www.science.co.il/Formula.asp