1
00:00:00,430 --> 00:00:04,429
In this video, we are going to revise how to change unit compression factors.

2
00:00:04,429 --> 00:00:10,429
This is something that we studied last year, but we are going to do a revision with these two examples.

3
00:00:10,429 --> 00:00:16,429
So, let's start. We want to know how many grams are there in 0.005 kilograms.

4
00:00:16,429 --> 00:00:24,429
What we need to do first is write in the information that we know that there are 0.05 kilograms.

5
00:00:24,429 --> 00:00:33,969
I'm going to write this here 0.05 kilograms okay this is what I have and I

6
00:00:33,969 --> 00:00:40,090
want to change to grams okay so I'm going to write this here and here sorry

7
00:00:40,090 --> 00:00:47,950
I shouldn't write this sign here this goes I have to multiply this number by a

8
00:00:47,950 --> 00:00:52,210
fraction this is the conversion factor okay the conversion factor should have

9
00:00:52,210 --> 00:00:58,030
the unit that we want to take out here. I will explain the reason for that and the

10
00:00:58,030 --> 00:01:04,709
unit that we want to have in the end over the line. And then I need to write

11
00:01:04,709 --> 00:01:12,950
numbers below and over the line so that below and over the line is the same. So we

12
00:01:12,950 --> 00:01:22,170
know that one kilogram is 1,000 grams and now the reason for writing

13
00:01:22,170 --> 00:01:27,329
kilograms below the line is that we multiply this by this. Kilograms cancel

14
00:01:27,329 --> 00:01:33,129
kilograms because they're in a fraction and I am left with grams. So I do the

15
00:01:33,129 --> 00:01:41,209
maths now. 0.05 times 1,000 is 50 grams. This is a simple example.

16
00:01:41,209 --> 00:01:44,689
let's go with something a little bit more difficult how many minutes are

17
00:01:44,689 --> 00:01:53,750
there in three days so in this case we start with three days and we want to

18
00:01:53,750 --> 00:02:01,730
change to minutes maybe you know how many minutes there are in a day but you

19
00:02:01,730 --> 00:02:09,539
normally don't know that don't know that you know that one day I'm going to write

20
00:02:09,539 --> 00:02:15,120
it here because you want to take it out has 24 hours okay so you can write this

21
00:02:15,120 --> 00:02:22,020
compression factor and then you also know the conversion between hours and

22
00:02:22,020 --> 00:02:32,840
minutes and you know that one hour is 60 minutes doing things like that you can

23
00:02:32,840 --> 00:02:38,120
see that days cancel days hours cancel hours and you are left only with minutes

24
00:02:38,120 --> 00:02:49,129
and now is what we are going to need our calculator okay so the name 3 times 24

25
00:02:49,129 --> 00:03:06,330
times 60 is this number 4000 what red red looks fine 320 minutes okay I'm

26
00:03:06,330 --> 00:03:13,469
going to give the calculator here from here because we are going to end with

27
00:03:13,469 --> 00:03:25,090
another example, another problem. First, I'm going to take out all of this. Maybe it's

28
00:03:25,090 --> 00:03:33,349
easier if I do this. Yes. And I'm going to show you another problem. Okay? It's a

29
00:03:33,349 --> 00:03:41,199
problem about this guy, Charlie. I'm going to put it here. Charlie who needs a new

30
00:03:41,199 --> 00:03:47,520
swimming costume. She knows her waist is 32 inches. She is probably American. She's

31
00:03:47,520 --> 00:03:52,159
ordering top-of-the-range streamlined wetsuits from Germany. Who only

32
00:03:52,159 --> 00:03:57,379
did deal with whole centimetres measurements. What size should

33
00:03:57,379 --> 00:04:03,259
she order? And we know that one inch is 254 centimetres.

34
00:04:03,259 --> 00:04:09,379
So what we want to do, basically, in this problem is to change from inches to

35
00:04:09,379 --> 00:04:14,800
centimetres, to know the appropriate, the right size in centimetres for Charlie.

36
00:04:14,800 --> 00:04:24,300
Okay, so again it's the same. We start with, we know, 32 inches. Inches are normally

37
00:04:24,300 --> 00:04:31,800
abbreviated like IN and we want to change that to centimeters. So we write

38
00:04:31,800 --> 00:04:37,459
the compression factor, okay, what we want to take out we put it below the line,

39
00:04:37,459 --> 00:04:46,879
centimeters over the line and we use this information one inch is 254

40
00:04:46,879 --> 00:04:58,819
centimeters again we use the calculator three times two point fifty four is so

41
00:04:58,819 --> 00:05:18,649
32 times 7.54, 32 times 2.54, now I have it right, that's 81.28.

42
00:05:18,649 --> 00:05:25,750
But remember, in Germany they only deal in whole centimeters, that means that I wouldn't count in the decimals.

43
00:05:26,209 --> 00:05:32,170
So the result for this problem is 81 centimeters.

44
00:05:33,269 --> 00:05:36,069
I hope this was helpful.

45
00:05:36,069 --> 00:05:37,269
See you next day in class.