Transcript Ranges of sizes, masses and times

IB Physics
Folders, text books, calculators,
data booklet.
Assessment
• Paper 1 (Multiple Choice) 20%
• Paper 2 (Extended response- some
choice) 32% SL, 36% HL
• Paper 3 (Options) 24% SL 20% HL
• Coursework SL-40 hours HL-60 hours
24%
Assessment
• Paper 1 (Multiple Choice) 45mins SL 1 hr
HL
• Paper 2 (Extended response- some
choice) 1¼ hr SL, 2¼ hr HL
• Paper 3 (Options) 1 hr SL 1¼ HL
• Coursework SL-40 hours HL-60 hours
Structure of course
• Year 12 – ALL standard level units (1 to 8)
• Year 13 – Options and HL units (9 – 14)
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Topic 1 – Physics and Physical
measurement
Use the syllabus
particularly when
studying for
examinations
The DEFINITIONS
you will have to
learn ‘by heart’.
Ranges of sizes,
masses and times
Order of magnitude
We can express small and large numbers
using exponential notation
The number of atoms in 12g of carbon is
approximately
600000000000000000000000
This can be written as 6 x 1023
Order of magnitude
We can say to the nearest order of
magnitude (nearest power of 10) that the
number of atoms in 12g of carbon is 1024
(6 x 1023 is 1 x 1024 to one significant figure)
Small numbers
Similarly the length of a virus is 2.3 x 10-8
m. We can say to the nearest order of
magnitude the length of a virus is 10-8 m.
Ranges of sizes, masses and times
You need to have an idea of the ranges of
sizes, masses and times that occur in the
universe.
Size
Can you think of 10 objects? Can you then
list them in order of decreasing length?
http://www.joemonster.org/gry/41805/Scale_of_the_Universe_2
Size
Which is the smallest on your list? What
size is it to the nearest order of
magnitude?
Size
The smallest objects that you need to
consider in IB physics are subatomic
particles (protons and neutrons).
These have a size (to the nearest order of
magnitude) of 10-15 m.
( 1 x 10-15m)
Size
Which is the largest on your list? How
large is it to the nearest order of
magnitude?
Size
The largest object that
you need to consider in
IB physics is the
Universe.
The observable Universe
has a size (to the
nearest order of
magnitude) of 1025 m.
Let’s try and get our head
around that!
•
http://www.joemonster.org/gry/41805/Scale_of_the_Universe_2
On your paper can you estimate the
masses of the largest and smallest
objects you have written?
Mass
The lightest particle you have to consider
is the electron. What do you think the
mass of the electron is?
-30
10
kg!
(0.000000000000000000000000000001 kg)
Mass
We have already decided that the
Universe is the largest object. What do
you think its mass is?
50
10
kg
(100000000000000000000000000000000000000000000000000 kg)
Time
Now think of 5 time intervals and put
them in order (longest first)
(For example, human lifetime, dog
lifetime, time to walk home etc.)
Time
The smallest time interval you need to
know is the time it takes light to travel
across a nucleus.
Can you estimate it?
-24
10
seconds
Time
What’s the longest time interval you
thought of?
Time
The age of the universe.
Any ideas?
Time
The age of the universe.
12 -14 billion years
1018 seconds
Copy please!
Size
10-15 m to 1025 m (subatomic particles to the
extent of the visible universe)
Mass
10-30 kg to 1050 kg (mass of electron to the
mass of the Universe)
Time
10-23 s to 1018 s (time for light to cross a
nucleus to the age of the Universe)
A common ratio – Learn this!
Hydrogen atom ≈ 10-10 m
Proton ≈ 10-15 m
Ratio of diameter of a hydrogen atom to its nucleus
= 10-10/10-15 = 105
Estimation
For IB you have to be able to make order
of magnitude estimates.
Estimation/Guess
What’s the
difference?
Estimate the following:
(to the nearest order of magnitude)
1. The mass of an apple
Estimate the following:
(to the nearest order of magnitude)
1. The mass of an apple
2. The number of times a human heart
beats in a lifetime.
Estimate the following:
(to the nearest order of magnitude)
1. The mass of an apple
2. The number of times a human heart
beats in a lifetime.
3. The speed a cockroach can run.
A fast South
American one!
Estimate the following:
(to the nearest order of magnitude)
1. The mass of an apple
2. The number of times a human heart
beats in a lifetime.
3. The speed a cockroach can run.
4. The number of times the earth will fit into
the sun (Rs = 6.96 x 108 m, Re = 6.35 x
106 m)
Estimate the following:
(to the nearest order of magnitude)
1. The mass of an apple 10-1 kg
2. The number of times a human heart
beats in a lifetime.
3. The speed a cockroach can run.
4. The number of times the earth will fit into
the sun (Rs = 6.96 x 108, Re = 6.35 x 106)
Estimate the following:
(to the nearest order of magnitude)
1. The mass of an apple 10-1 kg
2. The number of times a human heart
beats in a lifetime. 70x60x24x365x70=109
3. The speed a cockroach can run.
4. The number of times the earth will fit into
the sun (Rs = 6.96 x 108, Re = 6.35 x 106)
Estimate the following:
(to the nearest order of magnitude)
1. The mass of an apple 10-1 kg
2. The number of times a human heart
beats in a lifetime. 70x60x24x365x70=109
3. The speed a cockroach can run. 100 m/s
4. The number of times the earth will fit into
the sun (Rs = 6.96 x 108, Re = 6.35 x 106)
Estimate the following:
(to the nearest order of magnitude)
1. The mass of an apple 10-1 kg
2. The number of times a human heart
beats in a lifetime. 70x60x24x365x70=109
3. The speed a cockroach can run. 100 m/s
4. The number of times the earth will fit into
the sun (6.96 x 108)3/(6.35 x 106)3 = 106
Let’s do some more estimating!
Let’s do some more estimating!
Earth’s mass = 6 x 1024 kg