Transcript Ranges of sizes, masses and times

IB Physics
Folders, text books, calculators
• Paper 1 (Multiple Choice)
• Paper 2 (Extended response- some
choice)
• Paper 3 (Options)
• Coursework SL-40 hours HL-60 hours
Let’s have a ball!
Topic 1 – Physics and physical
measurement
Use the syllabus
particularly when
studying for
examinations
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 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
On your paper can you write in order of
decreasing size the names of 5 very small
things.
Size
Which is the smallest? 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.
Size
On your paper can you write in order of
increasing size the names of 5 very large
things.
Size
Which is the largest? 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 Universe has a size
(to the nearest order of
magnitude) of 1025 m.
Mass
On your paper can
you estimate the
masses of the 5
smallest objects
you wrote down
earlier.
Mass
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
small time intervals
(For example, the
time it takes sound
to travel 1 metre is
a small time
interval. Can you
think of smaller?)
Time
Can you add order of magnitude estimates
for your time intervals?
(For example, the time it takes sound to
travel 1 metre is 10-3 seconds to the
nearest order of magnitude)
Time
The smallest time interval you need to
know is the time it takes light to travel
across a nucleus.
Can you estimate it?
-23
10
seconds
Time
What’s the longest time interval you can
think of?
Time
The age of the universe.
Any ideas?
Time
The age of the universe.
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 (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.
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, Re = 6.35 x 106)
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, Re = 6.35 x 106)
5. The number of classrooms full of tea Mr
Porter will drink in his lifetime.
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)
5. The number of classrooms full of tea Mr
Porter will drink in his lifetime.
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)
5. The number of classrooms full of tea Mr
Porter will drink in his lifetime.
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)
5. The number of classrooms full of tea Mr
Porter will drink in his lifetime.
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
5. The number of classrooms full of tea Mr
Porter will drink in his lifetime.
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
5. The number of classrooms full of tea Mr
Porter will drink in his lifetime.
Let’s do some more estimating!