Monday, June 13, 2011

Density


It’s not a misspell, it is indeed Density and not Destiny because you are on my Science blog eh.

Okay, Density is defined as the mass per unit volume.

There was a running question (or joke - but not really funny), which is heavier 1 Kg of cotton or 1Kg of nail?

The obvious answer is- it both has the same weight.

But the correct question should be which is more dense?

And the correct answer is the nail.

Why?

Because although they have the same weight or mass (which is 1 Kg), the volume occupied by the cotton is more than the volume of the nail.

So let’s assume, the volume of cotton is 2 cm3 and nail is 0.5 cm3, the density of cotton and nail can be computed using the formula:

Density = mass/ volume

Density of cotton = 1 Kg/ 2 cm3 = 0.5 Kg/cm3

Density of nail = 1 Kg/ 0.5 cm3 = 2.0 Kg/cm3

Therefore, nail is more dense than cotton.

But I’ll give you a shorter way to determine which is more or which is less without the computation perse.

If you will submerge it with water, which one will sink and which one will float?

Of course the nail will sink and the cotton will float.

There goes the same answer, the nail is more dense while the cotton is less dense.

Why?

Because density of water is always 1 and used as THE standard.

So things (liquid or solid) with density more than 1 will sink,

While things (liquid or solid) with density less than 1 will float.

I always encourage people even myself to ask, because that’s how you learn things.

Gets?

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And while we’re on the topic, some use the word ‘dense’ to describe persons who cannot grasp things (like if your crush doesn’t understand your pa-cute ways)…

So when people call you dense don’t be happy about it because it means you’re less than 1 (the standard).

Gets?

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It’s been a whole year since my last post…

my apologies to my blog and my readers (if any)…

6 comments:

Liz said...

Wow. May update na. :)

Visiting BC Bloggers on my list. Hope you can do the same. Thanks!
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kay said...

This reminds me of my sisters blog hehe ... nakakatuwa naman :)

Traveller on a Shoestring said...

A lot of people always made a mistake when asked about these particular question- Which one is heavier 1 kilo of cotton or 1 kilo of iron nails?

A kg is a kg so they are the same.

This riddle only works for a pound of gold and a pound of feathers.

Precious metals such as gold are measured in troy weight. A troy pound is 12 troy ounces, and each troy ounce is 480 grains, making a total of 5760 grains to the pound of gold.

Most materials use pounds and ounces from the avoirdupois system, and such a standard pound is made up of 16 ounces, where each ounce is 437.5 grains, making a total of 7000 grains to the pound of feathers.

All this means that a "pound" of feathers (or bricks, or lead) is heavier than a "pound" of gold.

Wailing Soul said...

Wow!! This is my first time visiting a science blog :D hehe.. I think malayu mararating nito, keep sharing lang, dami mangangailangan nito in the future :D

Herbert

Gil Camporazo said...

The puzzle of "which is heavier a kilo of nail and a kilo of cotton" is common among high students or even math teachers themselves. But for science students, for science teachers they know which is "heavier" which it comes to density. This the confusion lies. Most students or even teachers regarded the nail as heavier that a cotton because of its "weight". What they really mean is the physical or the look of a nail, which unknowingly they are referring it its "density." Now I know how to explain to my 4 inquisitive grandchildren. Thanks!

Matsumoto Chan said...

ouch, let me be a cotton haha. keep this blog up ha...aliw!