is measuring volume and calculating density more accurate than water displacement?

Question

Do you think that determining the volume of your metal sample by measuring the dimensions (cm3) and calculating density would be more or less accurate than determining the volume by water displacement (mL) to calculate density? Explain.

Answer 1

Mya

This is an interesting question. The answer depends on the shape of the sample. Let's say your sample is a coin. Maybe one that is worn down so you can't detect the etched surface of the coin. you and calculate the volume of the sample by measuring the diameter and the thickness and using the formula for the volume of a cylinder. Your accuracy depends on the accuracy of the device you use to measure the dimensions (and your ability to measure the diameter exactly across the center of the coin.

Device that measure distance can be accurate to 0.0001 in

But, suppose the sample is a blob - maybe like a piece of chewed gum (I know - ick!). Now you don't have nicely defined dimensions to measure the volume - length, width, height - they are all pretty hard to determine. Now the water displacement measurement is likely to be more accurate than direct measurement of dimensions. The accuracy here depends on the accuracy of the device you use to

measure the water volume - before and after. Since you must measure difference between two measurements, your potential error is doubled.

Device to measure volume of water is usually a graduated cylinder, and are accurate to about 0.2% of the volume you are measuring.

In this case, Mass is Mass - any sample can be measured on a scale, regardless of the shape.

Hope this helps.