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Lesson 3. Prefixes

LESSON 3. PREFIXES

10^9 giga (G)

10^6 mega (M)

10^3 kilo (k)

10^-1 deci (d)
10^-2 centi (c)

10^-3 milli (m)

10^-6 micro (u) it was originally the squiggly u-like thing but I don't know how to type it! 

10^-9 nano (n) 

Prefixes x multiplication factor = Base Unit

Base unit / multiplication factor = Prefix

• 4kg = 4000g
• 0.03 m = 3 cm
• 2 x 10^-9 = 2

As the units get smaller, the value gets bigger OuO

Exercises! 

0.0002s in ms

0.0002/10^-3 = 0.2ms OR 0.2 x 10^-3 s = 0.2ms

480ug in mg

ug = 1/1000 000g --> (x1000) --> m = 1/1000g
= 0.480mg

7.2km in mm

7.2 km = 7200m

m = ^-3 (you add the 3 zeros behind!)

= 7 200 000mm 

36km/1hr (Convert 36km/h to m/s)
= 36 000m/3600s
= 10 m/s

Convert 6g/cm^3 into kg/m^3

6g/1cm^3

= 0.006kg / (0.01m)^3

= 6000kg/m^3

Force = mass x acceleration

= mass x (distance/time) / time 

Significant Numbers

Hi so this post would generally be a copy-paste post (where I just copy and paste everything important on the Google Doc given here!)

Uhm so here's the stuffs that are important (or at least I think is important. which is practically everything)
Here we go :)

SIGNIFICANT FIGURES

When we use an equipment to take measurement, it is important to be honest when reporting a measurement, so that it does not appear to be more accurate than the equipment used to make the measurement allows.  

To achieve this, we can control the number of significant figures used to report the measurement.

When we look at a number, its first significant figure is the first digit from the left, other than 0.  
The number of significant figures is the number of digits counting from the left from the first significant figures.

Rules for Significant Figures

• All non-zero numbers are significant
• All zeros between non-zero numbers are significant
• All zeros after the decimal points are significant
• Zeros used before the first non-zero digit are not significant
• Trailing zeros after the decimal points are significant. Trailing zeros before a decimal point may or may not be significant
• Leading zeros are not significant

When a measuring instrument is used to take a reading, it should be used to its full precision.

However, all physical instruments have a degree of uncertainty.  The uncertainty can be due to human error or due to the limitations of the measuring instrument.  When taking measurements, the degree of uncertainty can be indicated by recording the readings using the appropriate number of significant figures.

[!!!!] Normally the reading should be recorded to the smallest half division of the smallest scale of the instrument. (e.g., ammeter reading, measuring cylinder, etc)

In cases when taking measurement(s) that involved interval(s) e.g. measuring length using a metre rule (or protractor), we record to the smallest division.

The general rule is to round the answer to the least precise measurement used in the calculation

Not all values used in a calculation involved some uncertainties.  They may be counting numbers (pure numbers) or defined values, e.g. pi.  Hence, they could be ignored when working out the number of significant figures or decimal places during computation.

Revision Notes on Significant Figures <- Hi so this is the link for the actual google doc! I'm honestly torn or whether to let the public view this because this IS the Ms Siow's materials after all tsk tsk I should at least credit her if I want to share it with non Rafflesians right sighpie I'm not sure :< I'm setting the settings as Private so uhm idk if it comes to the point when an outsider wants to view it then we'll solve it then!