Volume, Weight

[Guest]

A steel bar is 2 1/2 feet in length, 4 1/2 inches wide, and 1 1/2 inches in thickness. Calculate volume and weight of bar.

Please check my calculations :

Volume - length x width x thickness

2.5 x .375 x .125 = .117 cu. ft.

Cubic foot of water = 62.5 lbs.

Specific gravity of steel = .785

.117 x 62.5 = 7.31

7.31 x .785 = 5.7403 = 6 lbs.

[Guest]

Please respond to my question. Thanks.

[Guest]

It seems that your calculations are OK.

[Guest]

Thanks.

[Guest]

From your first posting...............
....................
Please check my calculations :

Volume - length x width x thickness

2.5 x .375 x .125 = .117 cu. ft.

Cubic foot of water = 62.5 lbs.

Specific gravity of steel = .785

.117 x 62.5 = 7.31

7.31 x .785 = 5.7403 = 6 lbs.
...........................................

The specific gravity of steel is NOT .785
If it was then a bar of steel would float on water.............

The Specific gravity of steel is approx. 7.85
Almost 8 times heavier than water for the same volume.... so it sinks

So your calculation should be.....
7.31 x 7.85 = 57.38 lbs weight

[Guest]

Sorry for the typo...

I have a question:

Using specific gravity, can the weight of any substance be determined if the volume is known ?

[Guest]

Yes, all substances have a Specific Gravity. Another name for it is Relative Density. It is dimensionless ie. has no units because it is actually the ratio of 2 densities....Ratio of the density of the substance relative to the density of water.

As you stated in your post 1 cuft of water = 62.5 lbs in mass or weight. That means its density is 62.5 lbs per cuft.
And the relative density or Specific gravity of water is 1.00. so everything is compared to water.

[Guest]

Thanks for the info ....

[leesajohnson]

I think your calculation is correct.

[Guest]

Yes, the calculation that is correct, is correct.