Currently, I am doing a lab report for school and I have a few

questions. My teacher instructed us to find the density of an object,

such as a piece of lead, and the specific gravity. He said the

formulas were as follows: density=mass/volume (which i know is

correct) specific gravity=mass of object/displaced water of object

Now, I always thought the displaced water of the object, which I

already found, was the same as the volume of the object. Am I

correct? Because then the specific gravity would be equal to the

density, right? If you could e-mail me back ASAP, that would be

great. Thank you. Jennifer Slevin

```
Now, I always thought the displaced water of the object, which I
already found, was the same as the volume of the object. Am I
correct? Because then the specific gravity would be equal to the
density, right? If you could e-mail me back ASAP, that would be
great. Thank you. Jennifer Slevin
```

Hello Jennifer, the difference between density and specific gravity is

this:

Density is measured in units, for example kilogramms per cubic

decimeter, or other units.

Specific gravity is a mere number, applicable to any unit system,

comparing the weight of a substance of a certain volume to the weight

of the same volume of water.

If you use the metric system which is based on a kilogramm as the

mass of a cubic decimeter of water, your measurement of density of a

substance will be the same number as the specific gravity.

Many greetings, Regina

Here’s my response from work done in school. In general specific

gravity refers to the mass per unit volume of liquids; density refers

to the mass per unit volume of solids. It has to do with the way the

the mass per unit volume is measured. For liquids one uses an object

of known mass and volume and insert into the liquid to see how much

volume it displaces. For solids one can take water and use its

displacement to find of water to find its mass. Eureka said

Archimedes.

Of course all the usual caveats apply, and I stand to be corrected by

my fellow Orchideans.

David

```
Currently, I am doing a lab report for school and I have a few
questions. My teacher instructed us to find the density of an object,
such as a piece of lead, and the specific gravity. He said the
formulas were as follows: density=mass/volume (which i know is
correct) specific gravity=mass of object/displaced water of object
```

```
Now, I always thought the displaced water of the object, which I
already found, was the same as the volume of the object. Am I
correct? Because then the specific gravity would be equal to the
density, right? If you could e-mail me back ASAP, that would be
great. Thank you. Jennifer Slevin
```

G’day Jennifer; density is simply the same as specific gravity;

density is the name most often used by non scientists. Sorry to tell

you, but your teacher is a bit off the page! – Cheers now,

John Burgess; @John_Burgess2 of Mapua Nelson NZ

Jennifer: I know you have gotten other answers through Orchid.

However, such questions always interest me because I was not a

physics/chemistry student so I generally take the opportunity to brush

up on facts I don’t have at hand. My easiest source is to always go

to Google and simply plug in my question, in this case “definition of

density” and “definition of specific gravity”. Below are 3 of the

sites where I found understandable You may enjoy looking

at these and you may find that in the future it is faster for you to

simply go to Google and research for yourself.

http://www.essex1.com/people/speer/density.html

http://www.webelements.com/webelements/properties/text/definitions/den

sity.h tml

http://whatis.techtarget.com/definition/0,,sid9_gci751403,00.html

Thanks for bringing up a topic that caused me to go look it up.

Kay