(Sorry I am writing a lot of these posts many weeks later as I have been very busy so they may have slightly less details)
This week, we learnt about how to accurately describing the molecules in the three states of matter in terms of the attractive forces between the molecules, the distance between the molecules and the speed they move. We also learnt how to describe them using kinetic particle theory, including the change of state. We learnt the relationship between the speed of molecules and their temperature, as well as learning about plasma and bose-einstein condensate, their properties, and their conversions into the other states of matter (kinetic particle theory too).
_________________________________________________________________________________
There are 4 main characteristics of states of matter we look at here:
-shape
affected by arrangement of particles
-volume
affected by forces between particles and distance between particles
-compressibility
distance between particles
-whether brownian motion of a small particle can take place in it
affected by movement of particles
Solids:
Shape: fixed-particles closely packed together in fixed, regular pattern, occupying little space
Volume: fixed-particles vibrate about fixed positions and are held in position by very strong attractive forces
Compressibility: cannot be compressed as particles are too close together
Brownian motion-cannot take place
Liquids:
Shape: not fixed-particles slide past one another, free to move but confined within the vessel containing it
Volume: fixed-particles though they can slide past each other are still held together by attractive forces
Compressibility: cannot be compressed as particles are close together
Brownian motion-can take place
Gas:
Shape: not fixed-particles scattered freely throughout vessel in irregular pattern, occupying a lot of space
Volume: not fixed-particles have large distances between each other and can be squeezed closer together
Compressibility: can be compressed as particles are far apart
Brownian motion-can take place
We also learnt about two other states of matter-plasma and bose-einstein condensate.
Plasma is a state of matter consisting of free electrons and ions. These particles, unlike the other 3 states, can be controlled (e.g. plasma ball) using electrical and magnetic signals.
A plasma ball is a toy that is meant to mimic a tesla coil at a smaller scale. There is a coil of wires inside that have high frequency electrons vibrating. This vibration is so vigorous that the electrons are ripped off the atoms-forming plasma.
There are a few tricks you can do with a plasma ball.
The first is to put your hand on the plasma ball. A line of electricity similar to lightning will connect the core and the part of the glass your hand is touching. (You won't get electrocuted)
Placing a fluorescent light tube close to the plasma ball will ignite the light tube.
If you have two people, let one touch the plasma ball and the other hold a fluorescent tube. Holding the tube near to the person will cause it to light up as well.
In fluorescent lamps, electricity charges up mercury gas charging and exciting the atoms within-making the plasma emit light.
There is also Bose-Einstein condensate.
Firstly, all particles can be either bosons or fermions. All particles have a property known as spin, with fermions and bosons having fraction and whole number spins respectively. Thus fermions can be distinguished while bosons cannot. Bose-Einstein condensate only applies for bosons.
In Bose-Einstein condensate, there is no friction at all. Temperatures are extremely low (approaching 0) which makes these particles tend to form wave patterns.
Disclaimer: I told this to my father and he said the part about Bose-Einstein condensate is COMPLETELY WRONG! I am still not very sure what is right but Mr Tan you may want the teachers to confirm whether these facts are correct (he told me the wave thing is a COMPLETELY DIFFERENT CONCEPT from BSE)
Sunday, 27 April 2014
Term 2 Week 1
A New Term Begins...
This term, we did a lot of really fun and new stuff! Finally, on to some real Science! (After a short revision of last term's topics during the first lesson...)
This week, we learnt about Kinetic Particle Theory.
(a.k.a a big phrase to say that atoms are in continuous and random motion)
At first glance, the definition seems rather insignificant. Okay, they are constantly moving in no preset direction. What was so interesting, I thought.
Only later did I find out that the interesting part was the derivation of the theory.
Atoms are the smallest things on earth. At 10^-19m long (0.1-0.5 nanometres) they could not be seen even with the most powerful of the microscopes in the days when the theory was discovered. So during the time when we didn't have scanneling tunneling microscopes (which were only invented quite late and can see atoms), how did they even know about this theory?
The answer-brownian motion and diffusion.
Brownian motion affects everything, even us. Just that the effects on us are too small to be seen. Brownian motion is the resultant effect when we are bombarded by smaller particles. When we look through a microscope at dust particles (no not clumps of dirt but the much finer grains-but still can be seen through a normal microscope in those days), they are moving continuously and randomly. Even though there is no wind or other external force acting on them. So, how do they move?
This is because air particles, invisible to us, are constantly bombarding the dust particle at high speeds, thus resulting in the dust particle to move erratically. We can be sure that it is because of the air particles' bombardment because when the temperature rises, the motion of the dust particle increases because the air particles themselves move faster when they have more heat and thus kinetic energy.
Diffusion is the spreading of a substance throughout a fluid. When a drop of food colouring is dropped inside a cup of water, it quickly spreads throughout the liquid. This is because of kinetic particle theory. The particles of the substance move quickly, continuously and randomly thus spread throughout the water quickly yet without any identifiable pattern.
Here is a video on kinetic particle theory.
This term, we did a lot of really fun and new stuff! Finally, on to some real Science! (After a short revision of last term's topics during the first lesson...)
This week, we learnt about Kinetic Particle Theory.
(a.k.a a big phrase to say that atoms are in continuous and random motion)
At first glance, the definition seems rather insignificant. Okay, they are constantly moving in no preset direction. What was so interesting, I thought.
Only later did I find out that the interesting part was the derivation of the theory.
Atoms are the smallest things on earth. At 10^-19m long (0.1-0.5 nanometres) they could not be seen even with the most powerful of the microscopes in the days when the theory was discovered. So during the time when we didn't have scanneling tunneling microscopes (which were only invented quite late and can see atoms), how did they even know about this theory?
The answer-brownian motion and diffusion.
Brownian motion affects everything, even us. Just that the effects on us are too small to be seen. Brownian motion is the resultant effect when we are bombarded by smaller particles. When we look through a microscope at dust particles (no not clumps of dirt but the much finer grains-but still can be seen through a normal microscope in those days), they are moving continuously and randomly. Even though there is no wind or other external force acting on them. So, how do they move?
This is because air particles, invisible to us, are constantly bombarding the dust particle at high speeds, thus resulting in the dust particle to move erratically. We can be sure that it is because of the air particles' bombardment because when the temperature rises, the motion of the dust particle increases because the air particles themselves move faster when they have more heat and thus kinetic energy.
Diffusion is the spreading of a substance throughout a fluid. When a drop of food colouring is dropped inside a cup of water, it quickly spreads throughout the liquid. This is because of kinetic particle theory. The particles of the substance move quickly, continuously and randomly thus spread throughout the water quickly yet without any identifiable pattern.
Here is a video on kinetic particle theory.
Sunday, 6 April 2014
Term 1 Week 8
This week-summary week; we basically went over everything done in the past. (Also a little bit of new stuff)
Distance between every two dots=distance of 0.02 seconds of motion
For pendulum:
Fudicial line-an imaginary line in the centre of each swing
Oscillation-amount of time for pendulum to pass by fudicial line twice
Period-time for one oscillation
That's all for this term! See you next time!
(I feel like just putting the ppt here but that would be laziness)
Accuracy VS Precision
To make things clearer and easier I'll use a bulls-eye analogy
Accuracy-how close the darts are to the centre
Precision-how close the darts are to each other
Also known as: random error VS systematic error (respectively)
Length measurements:
Measuring tape and ruler-1 dp (cm)
Vernier caliper-2 dp (cm)
Micrometer screw gauge-3 dp (cm)/2 dp(mm)
Volume measurements:
Measuring cylinder-0.5 cm cube
Burette-0.05 cm cube
Pipette and volumetric flask-fixed volume
Meniscus-lowest/highest point of water level when viewed
For usual measurements e.g. measuring cylinder read concave (lower) meniscus
For mercury thermometer read convex (higher) meniscus
Area measurement: irregular figures:
Divide area into grid.
If square is fully filled, count it.
If square is more than half filled, count it.
If square is less than half filled, do not count it.
The smaller the squares, the greater the accuracy.
Measuring time:
Stopwatch:
Digital and analogue-digital more accurate measuring 2dp; analogue can only measure 1dp
However for stopwatch 2nd dp should not be counted because of human error-unless it is not a human starting and stopping the stopwatch
Human error=0.2-0.3s
Ticker-tape timer:
Electrical device using oscillations of a steel strip to measure short time intervals
Steel strip vibrates 50 times a second and makes 50 dots a second on a paper tape being pulled past it
Distance between every two dots=distance of 0.02 seconds of motion
For pendulum:
Fudicial line-an imaginary line in the centre of each swing
Oscillation-amount of time for pendulum to pass by fudicial line twice
Period-time for one oscillation
That's all for this term! See you next time!
Term 1 Week 7
This week, we played around with two main things-the vernier caliper and micrometer screw gauge.
Such complicated names.........
Scared me at first.
Lucky, they are just two other measuring instruments. The normal meter ruler can measure up to 0.1cm. The vernier caliper can measure up to 0.01 cm. The micrometer screw gauge can measure up to 0.001 cm (or 0.01 mm)
...so much more elaborate than a ruler. Both of them take quite a long process to measure when you compare with a ruler...
(I'm too lazy to explain the whole thing so here's a video on how both work)
I was wondering how to measure huge objects yet with great precision. Especially for things like rockets that require extraordinary precision. Do they have a giant vernier caliper...
Such complicated names.........
Scared me at first.
Lucky, they are just two other measuring instruments. The normal meter ruler can measure up to 0.1cm. The vernier caliper can measure up to 0.01 cm. The micrometer screw gauge can measure up to 0.001 cm (or 0.01 mm)
...so much more elaborate than a ruler. Both of them take quite a long process to measure when you compare with a ruler...
(I'm too lazy to explain the whole thing so here's a video on how both work)
I was wondering how to measure huge objects yet with great precision. Especially for things like rockets that require extraordinary precision. Do they have a giant vernier caliper...
Term 1 Week 6
This week, we learnt about indices/powers, especially of 10.
Why do we see these appearing in Science? Some measurements in Science are either very very big or very very small. Thus for certain things you will get measurements such as 70000000000000000 light years or 0.0000000000000000576mm for things such as distance between planets or size of atoms respectively (not exact measurements, just examples). However adding lots of zeros may result in errors because having 100 zeros and 101 zeros is a BIG difference in reality but in writing it is only one extra zero which some careless people might not notice. Secondly it is extremely tedious to write, again possibly resulting in error as well as wasting time. Can you imagine writing 100 zeros in each number sentence you write? Thus people have started to use powers of 10 to express the numbers in standard form.
10^0=1
10^1=10
10^2=100
10^3=1000
These are examples of powers of 10 (which if you do not already know) are numbers whereby 10 multiplies itself a few times such as 10^3 means 10 multiplied by itself 2 more times which is 1000. This also works for other numbers besides 10. Fortunately for powers of 10 whenever you multiply by 10 you just need to add a zero onto the original value making multiplying by 10 very east; to find ten to the power of x you just take a 1 and put x number of zeros behind it.
An example of a number in standard form: 1.287*10^6. A number in standard form is always a value from 1 to 9.999999999999... multiplied by a power of 10. The exponent can be positive or negative (but not a decimal or fraction). For example, 5678350000000=5.67835*10^12.
In this way, doing multiplication and division is also easier; even addition and subtraction.
Examples:
For multiplication:
(5.67*10^4)(3.91*10^7)
=(5.67*3.91)(10^4*10^7)
=22.1697*10^11---------4+7=11 so 11 is the exponent for the result; only works for powers of 10
=2.21697*10^11---------remember to convert the coefficient to a single digit number (not including dp)
For division:
(5.67*10^7)/(3.91*10^4)
~1.45*10^3--------------note how similarly the exponents can be subtracted to get the resultant exponent
For addition:
(5.67*10^7)+(3.91*10^4)
=(5.67*10^7)+(0.00391*10^7)-----raise smaller exponent to larger one and change coefficient accordingly
=5.67391*10^7
For subtraction:
(5.67*10^7)-(3.91*10^4)
=(5.67*10^7)-(0.00391*10^7)
=5.66609*10^7
Remember that all these operations can also be done for negative exponents.
_________________________________________________________________________________
However, to some people these numbers are meaningless. They don't really see much difference between 10^10 and 10^11. Thus we have prefixes.
Prefixes in English are phrases that can be added to the front of certain words that always change the meaning a certain way. Prefixes in Science work the same way, in a way multiplying the current value of that number by a certain power of 10. Some prefixes-kilo=10^3, mega=10^6, giga=10^9, milli=10^-3, nano=10^-9... the list goes on. The distance between most prefixes are multiples of 10^3 except hecto, deka, deci and centi, which are near one. Each of these prefixes has its own symbol.
58400000 grams (g)
=5.84*10^7 grams (g)
=58.4 Megagrams
0.00000764 metres (m)
=7.64*10^-6 metres (m)
=7.64 micrometres
_________________________________________________________________________________
The next lesson, we went to the Science lab. We did an experiment, but a rather unexciting one-timing pendulums.
We took a retort stand, tied a string to a weight then clamped the string tightly. We then displaced the weight at an angle then let it swing freely for a minute while counting the number of oscillations. Finally we divide the time by the number of oscillations to find the period, or the time for one oscillation. We then repeated the steps for different lengths of string.
After the experiment, our teacher Mr Tan explained to us A LOT of things that we had to take note during the experiment.
Firstly, the angle could not be too big. Otherwise the swinging could get rather erratic.
Secondly, we had to look at the pendulum from in front not from the side. Basically you couldn't observe it from the angle whereby it swings towards you. This is because the period is defined by the time between every two times it crosses the fudicial line which is basically the centre point of the swing. If you view it from the side then you couldn't really see when it actually crossed the fudicial line.
Thirdly you couldn't start the timer immediately after the pendulum first crossed the fudicial line! You had to wait a few swings before starting the timer so as to let the pendulum stabilise.
The hardest part of the experiment was probably to measure and tie the weight to the string. We had to either let more string or tie more string around the weight to increase and decrease the length of string respectively. However at times it would be not tight enough making the weight almost fall out! Thus we would have to retie the whole thing making it quite a tedious process. It also pretty hard to measure the string properly with the ruler, and we did not know where to start measuring because part of the string was inside the clamp!
_________________________________________________________________________________
That week, we had home-based learning, where we had to sit at home and use iVLE (our school e-learning platform) to listen to tutorials. Not as fun as learning in school...
Anyway, we learnt about mass, weight and density. (And a bit about gravity)
First, some definitions:
Mass-amount of substance in an object-measured in grams
Weight-force exerted by one object onto another due to gravity-measured in Newtons
*Note the difference between mass and weight-they are often confused
Density=mass/volume-can be considered as the concentration of substance inside the object for any specific volume
Gravitational field=a region whereby an object is affected by the force of gravity
(I can't define gravity yet though, sorry)
We also learnt that human reaction error time is from 0.2 to 0.3 seconds. I was thinking "so much?" Our NAPFA can change from a gold to a silver just because of a few milliseconds! It shocked me! Sadly there is no fixed error time so you can't like subtract a certain amount from your timing to get the real amount... if only there were some affordable equipment that can be more accurate...
Why do we see these appearing in Science? Some measurements in Science are either very very big or very very small. Thus for certain things you will get measurements such as 70000000000000000 light years or 0.0000000000000000576mm for things such as distance between planets or size of atoms respectively (not exact measurements, just examples). However adding lots of zeros may result in errors because having 100 zeros and 101 zeros is a BIG difference in reality but in writing it is only one extra zero which some careless people might not notice. Secondly it is extremely tedious to write, again possibly resulting in error as well as wasting time. Can you imagine writing 100 zeros in each number sentence you write? Thus people have started to use powers of 10 to express the numbers in standard form.
10^0=1
10^1=10
10^2=100
10^3=1000
These are examples of powers of 10 (which if you do not already know) are numbers whereby 10 multiplies itself a few times such as 10^3 means 10 multiplied by itself 2 more times which is 1000. This also works for other numbers besides 10. Fortunately for powers of 10 whenever you multiply by 10 you just need to add a zero onto the original value making multiplying by 10 very east; to find ten to the power of x you just take a 1 and put x number of zeros behind it.
An example of a number in standard form: 1.287*10^6. A number in standard form is always a value from 1 to 9.999999999999... multiplied by a power of 10. The exponent can be positive or negative (but not a decimal or fraction). For example, 5678350000000=5.67835*10^12.
In this way, doing multiplication and division is also easier; even addition and subtraction.
Examples:
For multiplication:
(5.67*10^4)(3.91*10^7)
=(5.67*3.91)(10^4*10^7)
=22.1697*10^11---------4+7=11 so 11 is the exponent for the result; only works for powers of 10
=2.21697*10^11---------remember to convert the coefficient to a single digit number (not including dp)
For division:
(5.67*10^7)/(3.91*10^4)
~1.45*10^3--------------note how similarly the exponents can be subtracted to get the resultant exponent
For addition:
(5.67*10^7)+(3.91*10^4)
=(5.67*10^7)+(0.00391*10^7)-----raise smaller exponent to larger one and change coefficient accordingly
=5.67391*10^7
For subtraction:
(5.67*10^7)-(3.91*10^4)
=(5.67*10^7)-(0.00391*10^7)
=5.66609*10^7
Remember that all these operations can also be done for negative exponents.
_________________________________________________________________________________
However, to some people these numbers are meaningless. They don't really see much difference between 10^10 and 10^11. Thus we have prefixes.
Prefixes in English are phrases that can be added to the front of certain words that always change the meaning a certain way. Prefixes in Science work the same way, in a way multiplying the current value of that number by a certain power of 10. Some prefixes-kilo=10^3, mega=10^6, giga=10^9, milli=10^-3, nano=10^-9... the list goes on. The distance between most prefixes are multiples of 10^3 except hecto, deka, deci and centi, which are near one. Each of these prefixes has its own symbol.
58400000 grams (g)
=5.84*10^7 grams (g)
=58.4 Megagrams
0.00000764 metres (m)
=7.64*10^-6 metres (m)
=7.64 micrometres
_________________________________________________________________________________
The next lesson, we went to the Science lab. We did an experiment, but a rather unexciting one-timing pendulums.
We took a retort stand, tied a string to a weight then clamped the string tightly. We then displaced the weight at an angle then let it swing freely for a minute while counting the number of oscillations. Finally we divide the time by the number of oscillations to find the period, or the time for one oscillation. We then repeated the steps for different lengths of string.
After the experiment, our teacher Mr Tan explained to us A LOT of things that we had to take note during the experiment.
Firstly, the angle could not be too big. Otherwise the swinging could get rather erratic.
Secondly, we had to look at the pendulum from in front not from the side. Basically you couldn't observe it from the angle whereby it swings towards you. This is because the period is defined by the time between every two times it crosses the fudicial line which is basically the centre point of the swing. If you view it from the side then you couldn't really see when it actually crossed the fudicial line.
Thirdly you couldn't start the timer immediately after the pendulum first crossed the fudicial line! You had to wait a few swings before starting the timer so as to let the pendulum stabilise.
The hardest part of the experiment was probably to measure and tie the weight to the string. We had to either let more string or tie more string around the weight to increase and decrease the length of string respectively. However at times it would be not tight enough making the weight almost fall out! Thus we would have to retie the whole thing making it quite a tedious process. It also pretty hard to measure the string properly with the ruler, and we did not know where to start measuring because part of the string was inside the clamp!
_________________________________________________________________________________
That week, we had home-based learning, where we had to sit at home and use iVLE (our school e-learning platform) to listen to tutorials. Not as fun as learning in school...
Anyway, we learnt about mass, weight and density. (And a bit about gravity)
First, some definitions:
Mass-amount of substance in an object-measured in grams
Weight-force exerted by one object onto another due to gravity-measured in Newtons
*Note the difference between mass and weight-they are often confused
Density=mass/volume-can be considered as the concentration of substance inside the object for any specific volume
Gravitational field=a region whereby an object is affected by the force of gravity
(I can't define gravity yet though, sorry)
We also learnt that human reaction error time is from 0.2 to 0.3 seconds. I was thinking "so much?" Our NAPFA can change from a gold to a silver just because of a few milliseconds! It shocked me! Sadly there is no fixed error time so you can't like subtract a certain amount from your timing to get the real amount... if only there were some affordable equipment that can be more accurate...
Saturday, 5 April 2014
Term 1 Week 5
This week, we have been learning physical quantities and units. If you have a certain amount of substance, or any other thing such as length, volume, time, how are you going to represent them? Furthermore, how are you going to ensure that the way you represent that particular amount of substance/time etc is the same universally? Thus we need units. Units are used firstly to tell the viewer what is being measured, then how much of it. Examples are cm, kg etc. These units are universal so that if one scientist in Singapore says that this substance is 100kg, a scientist in America knows exactly what him or her is talking about. In the past, we had different units across the globe thus sharing information was rather difficult. Furthermore the measurement system was much more complicated. The difference in magnitude between units was quite random, for example from one unit to the next would be *6, then *22 to the next, especially when measuring volume. This made conversion very difficult. Nowadays, out units are mostly if not all in increments of powers of 10 which makes conversion much easier since you only had to add or subtract zeros. Till this day, some measurements such as length are still slightly different across the globe, with the main two scales being cm and inches which are not related in increments of powers of 10.
Base quantities-mass (kg), length (m), time (s), current (A), temperature (K), amount of substance (mol), light intensity (cd) which stand for kilograms, metres, seconds, amperes, kelvin, moles and candelas respectively. These base quantities are all the quantities that are not derived, meaning that they are not a product or quotient of two other quantities. Examples of non base quantities are Newtons, speed, acceleration etc which are measured in kg/m/s^2, m/s and m/s^2 respectively. These are all SI units, the set of units recognised worldwide (note: not including inches) and are the main scale used when measuring objects.
Base quantities-mass (kg), length (m), time (s), current (A), temperature (K), amount of substance (mol), light intensity (cd) which stand for kilograms, metres, seconds, amperes, kelvin, moles and candelas respectively. These base quantities are all the quantities that are not derived, meaning that they are not a product or quotient of two other quantities. Examples of non base quantities are Newtons, speed, acceleration etc which are measured in kg/m/s^2, m/s and m/s^2 respectively. These are all SI units, the set of units recognised worldwide (note: not including inches) and are the main scale used when measuring objects.
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