1. Name the units for the following quantities:
Lesson link
Name the units for the following quantities:
Current
Charge
Velocity
Distance
Force
Energy

2. Units, Quantities and Significant Figures
28/11/2018
c/w
Units, Quantities and Significant Figures

3. Learning Objectives
Developing Recall and use the SI units for physical quantities
Securing Recall and use multiples and sub-multiples of units
Exceeding
Be able to convert different units and use significant figures

4. Engage Systeme Internationale
Sounds fancy right? The systeme internationale is a list of the standard units that we should use in physics
For example, we should measure distance in metres not in ‘kilometers’ or ‘parsecs’ or ‘cats in a row’
You are expected to learn all of the standard units. If something is given in a different unit, you simply convert it first
Metre (for distance)
Kilogram (for mass)
Second (for time)
Ampere (for current)
Kelvin (for temperature)
Pico -12
Nano -9
Micro -6
Milli-3
centi -2
Kilo 3
Mega 6
Giga 9

5. For example: the radius of the sun is 659700000m
Engage
Standard form
Often, numbers are too big or too small to write out in full, even if you round to significant figures
For example: the radius of the sun is m
So what we do is use standard form. Standard form summarises the number into a form ending in ‘x10’ to a certain power.
For example:
300,000 would be 3 x 105
0.006 would be 6 x 10-3
5689 would be 5.7 x 103
So, for large numbers look for the number of digits after the first digit and for small ones, the number of digits after the decimal place!
Pico -12
Nano -9
Micro -6
Milli-3
centi -2
Kilo 3
Mega 6
Giga 9

6. Engage
Standard form
Complete the following sheets. Write your answers on the sheet and stick the sheet in your book
Useful note:
There is a ‘x10’ button on the bottom of most calculators (sometimes shown as ‘EXT’
Pico -12
Nano -9
Micro -6
Milli-3
centi -2
Kilo 3
Mega 6
Giga 9

7. Explore Orders of Magnitude
Certain powers of 10 (e.g. x103) are known as orders of magnitude and are just easy ways of keeping the numbers in set categories that are easy to say.
For instance, you’re used to the word kilometre, and that’s actually using the prefix ‘kilo’ which means 1000 (or x103)
Pico -12
Nano -9
Micro -6
Milli-3
centi -2
Kilo 3
Mega 6
Giga 9
1 millilitre
1 litre
1 kilolitre

8. Explore
Put these orders of magnitude in order from smallest to largest and link them to their power
Giga (G)
Kilo (K)
Mega (M)
Milli (m)
pico (p)
Micro (μ)
Centi (c)
Nano (n)
Pico -12
Nano -9
Micro -6
Milli-3
centi -2
Kilo 3
Mega 6
Giga 9
10-12
10-9
10-6
10-3
10-2
103
106
109

9. Explore
Copy out this list into your book and be very neat as you’ll need to refer back to it in future!
10-12
10-9
10-6
10-3
10-2
103
106
109
pico (p)
Nano (n)
Micro (μ)
Milli (m)
Centi (c)
Kilo (K)
Mega (M)
Giga (G)
Pico -12
Nano -9
Micro -6
Milli-3
centi -2
Kilo 3
Mega 6
Giga 9
Let’s consider the height of something, work in pairs to think of something that would have their height measured in each order of magnitude

10. 10-12
10-9
10-6
10-3
10-2
103
106
109
pico (p)
Nano (n)
Micro (μ)
Milli (m)
Centi (c)
Kilo (K)
Mega (M)
Giga (G)

11. Explore Converting orders of Magnitude
Very frequently, physics exams will expect you to convert units. They won’t always tell you to do it, its up to you to see if the unit given isn’t the standard unit
For instance, quite often you’ll be given mA instead of A for current. So you’ll need to convert it first!
This is super easy, you just need to remember your order of magnitude value!
So as you know that ‘milli’ means “x 10-3” then 15mA is 15x10-3A
Have a go!
Convert 45mA into A
Convert 76GA into A
Convert 25km into m
Convert 12pN into N
Convert 34nm into m
Pico -12
Nano -9
Micro -6
Milli-3
centi -2
Kilo 3
Mega 6
Giga 9

12. Explore Significant Figures
These are important as they can be the difference between the mark for a calculation.
The word significant means: having meaning.
With the number 368249, the 3 is the most significant digit, because it tells us that the number is 3 hundred thousand and something. It follows that the 6 is the next most significant, and so on.1
With the number  , the 5 is the most significant digit, because it tells us that the number is 5 millionths and something. The 8 is the next most significant, and so on.
Pico -12
Nano -9
Micro -6
Milli-3
centi -2
Kilo 3
Mega 6
Giga 9

13. Explore Significant Figures
We round off a number using a certain number of significant figures.
The most common are 1, 2 or 3 significant figures.
Remember the rules for rounding up are the same as before:
“If the next number is 5 or more, we round up”.
  correct to 1 significant figure?
 0.002
  correct to 1 significant figure?
0.04
Complete the sig figs sheet
  correct to 2 significant figures?
0.036
 7.994 to two significant figures?
8.0

14. Learning Objectives
Developing (3) Recall and use the SI units for physical quantities
Securing (4-6) Recall and use multiples and sub-multiples of units
Exceeding (7-9)
Be able to convert different units and use significant figures

15. Complete all questions on all worksheets provided
Independent Study
Complete all questions on all worksheets provided