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Chemistry: 3.7 Density 154 Views
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Description:
Having trouble with density? Don't worry, you're not dense. It's just a bit of a dense topic. Take a look at this video and we'll tell you everything you need to know.
Transcript
- 00:03
Meet Mortimer Thumb he's Tom thumb's lesser-known little brother [Mortimer waving next to his brother]
- 00:08
emphasis on little. For the past year Mortimer has been building his own boat
- 00:13
he dreams of setting sail in steering his homemade ship from one end of a
- 00:18
beaker filled with water to the other. When you're Mortimer's size well it's
- 00:22
safer to dream small. He finally completes his cube-shaped boat and is
Full Transcript
- 00:26
ready for the adventure of his lifetime, but he's a bit nervous he really doesn't [Mortimer looking apprehensive]
- 00:31
want his boat to sink. So to determine whether or not his boat will float he
- 00:36
has to consider its density and compare it to the density of water. Well the
- 00:41
formula for density is just mass divided by volume. Mortimer knows that if his
- 00:47
boat is less dense than water it'll float if it's denser than water, well then [Boat floating and then it sinks]
- 00:52
not so much... He knows that the density of water is one gram per cubic centimeter
- 00:57
even if he didn't know he could figure it out the beaker is a 500 milliliter
- 01:03
beaker full of water. 1 milliliter is the same as a centimeter cubed so the beaker
- 01:09
can hold 500 cubic centimeters of water well if Mortimer could get a big person
- 01:14
to help him measure the mass of the water, he'd find that it comes out to 500 [The beaker of water is put on a scale]
- 01:19
grams well 500 grams divided by 500 cubic centimeters reduces to 1 gram over
- 01:24
one cubic centimeter so there you go. All right now for the boat. Mortimer takes a
- 01:29
couple of separate measurements first he finds the mass of his little boat
- 01:33
plopping it onto the scale he discovers that the 'Voyager' weighs in at exactly 15
- 01:39
grams. Next he finds the volume of his boat he knows that the volume of the
- 01:44
cube is the area cube so he starts by finding the area of one side of his [Mortimer measuring up his boat]
- 01:49
little boat there, four centimeters times four centimeters is 16 centimeters and
- 01:54
since he then has to multiply by the depth of the cube, so four centimeters
- 01:59
there as well, it looks like the volume of his boat is 64 cubic centimeters.
- 02:05
All right now using the density formula, Mortimer takes the mass 15 [Board showing Mortimer's working]
- 02:09
grams and divides it by the volume 64 cubic centimeters and he winds up with point
- 02:15
23 grams per cubic centimeter meaning that the density of his vessel is much
- 02:21
less than the density of water so this puppy is going to float. Happily Mortimer
- 02:26
drops his boat into the beaker of water and hops in ready for the adventure of a [Mortimer chucks his boat in and then jumps in himself]
- 02:31
lifetime, unfortunately he sort of forgot to take into account his own mass... [Mortimer and his boat sink]
- 02:37
Oh well, little man overboard.
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