answers to word problems from friday on pg 72 :)
Monday, March 28, 2011
Tuesday, March 8, 2011
If At First You Don't Succeed, Try, Try Again
Today was basically the first day we started kinematics or in other words the motion unit. Mr.Chung had divided us in 7 groups and I was chosen as the leader. My job was to setup the equipment and explain to my group members what we were suppose to do and how. They got the hang of it pretty fast! The objective of the activity was to match our walking patterns to the pattern of the distance-time graphs or velocity-time graphs using a motion detector.
A. Stand at 1m away from the origin and stay at rest for 1s
B. Jog 1.5 m [E] away from the origin in 2s at a constant speed
C. Stand 2.5 m away from the origin for 3s
D. Jog 0.75 m [W] toward the origin in 1.5s at a constant speed
E. Stand at 1.75 m away from the origin and stay at rest for 2.5 s
A. Start at a distance of 3 m away from the origin and jogs 1.5 m [W] toward the origin in 3s at a constant speed
B. Stand 1.5 m away from the origin and stay at rest for 1s
C. Jog 1 m [W] toward the origin in 1s
D. Stand 0.5 m away from the origin and stay at rest for 2s
E. Jog 2.5 m [E] away from the origin in 3s
A. Stay at a velocity of 0 (rest) for 2s
B. Speed is increased to 0.5 m/s [E] during 0.1 s
C. Speed of 0.5 m/s [E] is maintained for 2.9 s
D. Object quickly speeds up in 0.1 s at 0.5 m/s [W]
E. Stay at a velocity of 0 (rest) for 1.9 s
F. Speed is increased to 0.5 m/s [W] during 0.1 s
G. Speed of 0.5 m/s [W] is maintained for 2.9 s
A. Increase to a speed of 0.5 m/s [E] going away from the origin for 4s
B. Maintain speed of 0.5 m/s [E] for 2s
C. Speed is at 0 m/s [W] during the 0.1 s
D. Maintain a speed of 0.4 m/s [E] for 3.9 s
E. Speed up for 0.1 s at a speed of 0.4 m/s [E]
F. Stay at a velocity of 0 (rest) for 0.9 s
A. Stand about 0.8 m [E] away from the origin and jog 1m away from the origin for 3.5 s
B. Stand 1.8 m [E] away from the origin and stay at rest for 3 s
C. Jog 1.5 m [E] away from the origin in 3.5 s
Some things to know:
D-T Graphs (B,C, F)
-If the slope is inclining, walk away from the origin
-If there is no change in the line (slope of 0), stay still
-If the slope is declining, walk toward the origin
-The speed at which you have to walk depends on the time you have to walk it in
V-T Graphs (D, E)
-If there is no change in the line (slope of 0), the speed is constant
-If the velocity is at 0, there is no movement
-If the line inclines or declines, there is an indication that the speed is changing
Reading D-T or V-T graphs can be quite confusing. Therefore, you should carefully analyze the graphs.
 |
| The result for graph B |
B. Jog 1.5 m [E] away from the origin in 2s at a constant speed
C. Stand 2.5 m away from the origin for 3s
D. Jog 0.75 m [W] toward the origin in 1.5s at a constant speed
E. Stand at 1.75 m away from the origin and stay at rest for 2.5 s
 | |
| The result for graph C |
B. Stand 1.5 m away from the origin and stay at rest for 1s
C. Jog 1 m [W] toward the origin in 1s
D. Stand 0.5 m away from the origin and stay at rest for 2s
E. Jog 2.5 m [E] away from the origin in 3s
 | |||
| The result for graph D |
B. Speed is increased to 0.5 m/s [E] during 0.1 s
C. Speed of 0.5 m/s [E] is maintained for 2.9 s
D. Object quickly speeds up in 0.1 s at 0.5 m/s [W]
E. Stay at a velocity of 0 (rest) for 1.9 s
F. Speed is increased to 0.5 m/s [W] during 0.1 s
G. Speed of 0.5 m/s [W] is maintained for 2.9 s
 |
| The result for Graph E |
B. Maintain speed of 0.5 m/s [E] for 2s
C. Speed is at 0 m/s [W] during the 0.1 s
D. Maintain a speed of 0.4 m/s [E] for 3.9 s
E. Speed up for 0.1 s at a speed of 0.4 m/s [E]
F. Stay at a velocity of 0 (rest) for 0.9 s
 |
| The result for Graph F |
B. Stand 1.8 m [E] away from the origin and stay at rest for 3 s
C. Jog 1.5 m [E] away from the origin in 3.5 s
Some things to know:
D-T Graphs (B,C, F)
-If the slope is inclining, walk away from the origin
-If there is no change in the line (slope of 0), stay still
-If the slope is declining, walk toward the origin
-The speed at which you have to walk depends on the time you have to walk it in
V-T Graphs (D, E)
-If there is no change in the line (slope of 0), the speed is constant
-If the velocity is at 0, there is no movement
-If the line inclines or declines, there is an indication that the speed is changing
Reading D-T or V-T graphs can be quite confusing. Therefore, you should carefully analyze the graphs.
Thursday, February 24, 2011
Opposites Attract Creating A Force...
We recently started our new unit on magnetism. Starting from elementary school, we all have played with magnets; knowing that like poles (same charge) repel and unlike poles (opposite poles) attract. To test this theory we used a compass to detect the direction of north and south using a magnet. It was not showing expected results; the north was attracting to the north and south to the south. So we learnt that the earth's actual north pole is not in the arctic it is in the antarctic and the south is actually in the arctic. This concept can be more clearly observed in the below diagram.
Scientists in the early days were trying to research force at a distance which was the common element between electrostatics and magnetism. Among one of them was Hans Christian Oersted. While conducting his research, he discovered something very significant which came to be known as Oersted's Principle.
Oersted's Principle: Charge moving through a conductor produces a circular magnetic field around the conductor
Using this knowledge from Oersted, scientists were able to develop right-hand rules (called right hand because the use of the right hand is involved).
Right Hand Rule # 1: If the right hand is placed around the conductor with the thumb pointing in the direction of conventional current flow, or positive (+) current flow, the fingers will curl in the same direction as the magnetic field.
Right Hand Rule # 2: The fingers curl in the direction of conventional current, or positive (+) current flow and the thumb points in the direction of the magnetic field within the coil. Outside the coil, the thumb represents the north (N) end of the electromagnet produced by the coil.
Later we can learn how these two rules strengthen our knowledge of magnetism and can enable us to make things move using electricity such as a motor!
 |
| This constant change in the magnetic fields is causing animals who have natural sense of direction to lose their way and eventually leads to their death. |
Oersted's Principle: Charge moving through a conductor produces a circular magnetic field around the conductor
Using this knowledge from Oersted, scientists were able to develop right-hand rules (called right hand because the use of the right hand is involved).
Right Hand Rule # 1: If the right hand is placed around the conductor with the thumb pointing in the direction of conventional current flow, or positive (+) current flow, the fingers will curl in the same direction as the magnetic field.
 |
| In this case the thumb is pointing upwards and the fingers are curled pointing to the right. This indicates that the magnetic fields will go to the right in other words counter clockwise. |
 |
| In this case the fingers are curled upwards, making the thumb point to the left. This indicates that the north (N) pole is on the left side of the coil. |
Wednesday, February 16, 2011
The Art of Concept Maps
Today we learnt about concept mapping. It may sound easy, but it is quite the opposite. First of all it is necessary to understand clearly all the topics you are dealing with in order to determine their relationships with each other. As if it wasn't already difficult, we were told to create a concept map with our group without any forms of written or verbal communication i.e no speaking, writing, etc... The concepts we were trying to link and describe was current, voltage, power, and circuit laws.
This is a picture of the end result of our concept map:
10 things to remember when dealing with electricity:
1) First of all what is electricity?
Electricity is a flow of electrons around a circuit.
2) Current is the rate of charge flow between two points measured in coulombs per second. This unit for current is amperes which is symbolized by I. Current can be measured by a device known as an ammeter. The general formula for current is as follows:
I = charge (Q)
-----------
time (t)
3) Voltage is known as electric potential difference which is measured in volts. The voltage between two points can be measured by a device known as a voltmeter. Voltage is defined by energy/charge :
V = E (in joules)
--------------
Q (charge)
4) Difference between series and parallel circuits
A series circuit is an electric circuit arranged so that the current passes through all of the loads in one unbranched pathway
and...
in a parallel circuit the electric circuit is arranged with parallel loads that are connected side by side where electric current can flow through multiple pathways
5) Circuit Laws
Resistance in Series:
From Kirchhoff's Law: VT = V1 + V2 + V3 = VN
IT = I1 = I2 = I3 = IN
From Ohm's Law : RT = R1 + R2 + R3 = RN
Resistances in Parallel:
From Kirchhoff's Law: IT = I1 + I2 + I3 + IN
VT = V1 = V2 = V3 = VN
From Ohm's Law : 1 1 1 1
-- = -- = -- = --
RT R1 R2 R3
6) Power is the rate at which work is done which can be defined by:
P = IV OR V2
-----
R
The unit for power is watts or (w).
7) Energy is work done in joules which can be measured by :
E= VIT
8) The unit of charge is coulombs which can be defined as a group of electrons. 1 C= 6.24 X 10^18 and the charge of one electron is 1.60 X 10^-19 C.
9) Resistance is the opposition to current flow which can be defined by using the following equation:
R = V
--
I
The unit for resistance is ohms (Ω).
10) Two theories describing energy transfer:
Conventional Current - This theory was developed by Benjamin Franklin. This is the model of positive current flow which states that electrons move from the positive (+) terminal, through the circuit, to the negative (-) terminal.
However, we know today that this theory is wrong but use it anyway because it is too late to change the way we regard energy flow. The correct theory is known as electron flow.
Electron Flow- states that electrons move from the negative (-) terminal, through the circuit, to the positive (+) terminal.
Look how the whole unit of electricity can be briefly summed up in just about 10 points!
This is a picture of the end result of our concept map:
10 things to remember when dealing with electricity:
1) First of all what is electricity?
Electricity is a flow of electrons around a circuit.
2) Current is the rate of charge flow between two points measured in coulombs per second. This unit for current is amperes which is symbolized by I. Current can be measured by a device known as an ammeter. The general formula for current is as follows:
I = charge (Q)
-----------
time (t)
3) Voltage is known as electric potential difference which is measured in volts. The voltage between two points can be measured by a device known as a voltmeter. Voltage is defined by energy/charge :
V = E (in joules)
--------------
Q (charge)
4) Difference between series and parallel circuits
A series circuit is an electric circuit arranged so that the current passes through all of the loads in one unbranched pathway
and...
in a parallel circuit the electric circuit is arranged with parallel loads that are connected side by side where electric current can flow through multiple pathways
5) Circuit Laws
Resistance in Series:
From Kirchhoff's Law: VT = V1 + V2 + V3 = VN
IT = I1 = I2 = I3 = IN
From Ohm's Law : RT = R1 + R2 + R3 = RN
Resistances in Parallel:
From Kirchhoff's Law: IT = I1 + I2 + I3 + IN
VT = V1 = V2 = V3 = VN
From Ohm's Law : 1 1 1 1
-- = -- = -- = --
RT R1 R2 R3
6) Power is the rate at which work is done which can be defined by:
P = IV OR V2
-----
R
The unit for power is watts or (w).
7) Energy is work done in joules which can be measured by :
E= VIT
8) The unit of charge is coulombs which can be defined as a group of electrons. 1 C= 6.24 X 10^18 and the charge of one electron is 1.60 X 10^-19 C.
9) Resistance is the opposition to current flow which can be defined by using the following equation:
R = V
--
I
The unit for resistance is ohms (Ω).
10) Two theories describing energy transfer:
Conventional Current - This theory was developed by Benjamin Franklin. This is the model of positive current flow which states that electrons move from the positive (+) terminal, through the circuit, to the negative (-) terminal.
However, we know today that this theory is wrong but use it anyway because it is too late to change the way we regard energy flow. The correct theory is known as electron flow.
Electron Flow- states that electrons move from the negative (-) terminal, through the circuit, to the positive (+) terminal.
Look how the whole unit of electricity can be briefly summed up in just about 10 points!
Thursday, February 10, 2011
Two Great Minds Think Alike
Lately, I have learnt about two physicists that are considered noteworthy. The two people are Georg Simon Ohm and Gustav Robert Kirchhoff.
Ohm discovered that there was a proportional relationship between the voltage and the current that always calculated the same value for resistance (separate from other variables i.e temperature, calculation error). He came up with a general formula to represent the resistance and this was named the Ohm's Law.
Ohm's Law : R = V
--
I
where R is the resistance in volts/ ampere
Kirchhoff studied the way current and voltage was affected in series and parallel circuits respectively. He came up with two laws that we know as today:
Kirchhoff's Current Law: The total amount of current into a junction point of a circuit equals the total current that flows out of the same junction
Kirchhoff's Voltage Law: The total of all electric potential decreases in any complete circuit loop is equal to any potential increases in that circuit loop.
Kirchoff's laws are improvements made on two other laws:
Conservation of Electric Charge: a law stating that the quantity of electric charge, the amount of positive charge minus the amount of negative charge in the universe, is always conserved
Conservation of Energy: a law stating that the total amount of energy in an isolated system remains constant over time, in other words conserved over time
Here are some important formulas to know to calculate current, voltage, or resistance in series circuits using the Ohm or Kirchhoff laws.
Resistance In Series:
From Kirchhoff's Law: VT = V1 + V2 + V3 = VN
IT = I1 = I2 = I3 = IN
From Ohm's Law : RT = R1 + R2 + R3 = RN
In addition, if all the values of all the resistors in a series circuit are the same, the overall resistance can be determined by
RT = NR
where the total resistance is calculated by multiplying the total number of resistors (N) by the resistance of each individual resistor (R)
Resistances in Parallel:
From Kirchhoff's Law: IT = I1 + I2 + I3 + IN
VT = V1 = V2 = V3 = VN
From Ohm's Law : 1 1 1 1
-- = -- = -- = --
RT R1 R2 R3
In addition, if all the values of all the resistors in a parallel circuit are the same, the overall resistance can be determined by
RT = R
---
N
where the total resistance is calculated by divided the resistance of each individual resistor (R) by the total number of resistors (N)
Ohm discovered that there was a proportional relationship between the voltage and the current that always calculated the same value for resistance (separate from other variables i.e temperature, calculation error). He came up with a general formula to represent the resistance and this was named the Ohm's Law.
Ohm's Law : R = V
--
I
where R is the resistance in volts/ ampere
Kirchhoff studied the way current and voltage was affected in series and parallel circuits respectively. He came up with two laws that we know as today:
Kirchhoff's Current Law: The total amount of current into a junction point of a circuit equals the total current that flows out of the same junction
 |
| The current entering any junction is equal to the current leaving that junction. i1 + i4 = i2 + i3 |
Kirchhoff's Voltage Law: The total of all electric potential decreases in any complete circuit loop is equal to any potential increases in that circuit loop.
 |
| The sum of all the voltages around the loop is equal to zero. v1 + v2 + v3 - v4 = 0 |
Conservation of Electric Charge: a law stating that the quantity of electric charge, the amount of positive charge minus the amount of negative charge in the universe, is always conserved
Conservation of Energy: a law stating that the total amount of energy in an isolated system remains constant over time, in other words conserved over time
Here are some important formulas to know to calculate current, voltage, or resistance in series circuits using the Ohm or Kirchhoff laws.
Resistance In Series:
From Kirchhoff's Law: VT = V1 + V2 + V3 = VN
IT = I1 = I2 = I3 = IN
From Ohm's Law : RT = R1 + R2 + R3 = RN
In addition, if all the values of all the resistors in a series circuit are the same, the overall resistance can be determined by
RT = NR
where the total resistance is calculated by multiplying the total number of resistors (N) by the resistance of each individual resistor (R)
Resistances in Parallel:
From Kirchhoff's Law: IT = I1 + I2 + I3 + IN
VT = V1 = V2 = V3 = VN
From Ohm's Law : 1 1 1 1
-- = -- = -- = --
RT R1 R2 R3
In addition, if all the values of all the resistors in a parallel circuit are the same, the overall resistance can be determined by
RT = R
---
N
where the total resistance is calculated by divided the resistance of each individual resistor (R) by the total number of resistors (N)
Tuesday, February 8, 2011
You spin my head right round :)
I skimmed through some of the roller coasters made in the past few years. There were a few that caught my eye quickly and I really admired the creativity and the hard work put into it. You can see these below !!!
 |
| Well since I have grown up playing Mario, I found this one cute :) |
 |
| I think the ship idea was different! |
 |
| I like how complex this team made their coaster.. quite nice!! |
 |
| I've always had an interest in greek mythology ;) |
 |
| This one was my favourite one! All of the wonders of the world are beautiful and creative and I found this coaster to fit both of the categories :D |
Monday, February 7, 2011
Go with the flow ;)
Today we learnt about energy flow in circuits. The flow of charge is referred to as electric current.
Electricity is demonstrated by a steady flow of electrons. As electrons move around a circuit, they transfer electric charge with them too.
The current can be measured by using this general formula :
I = charge (Q)
-----------
time (t)
I= Current in amperes
Because the size of an electron is very minute (2.82 x 1015 m )
scientists decided to measure electron in groups referred to as couloumbs. One coulomb is 6.25 x 1018
electrons.
Lets looks at batteries. You start off with chemical energy which separates the electrons from the atoms. As they continue to separate, there is a charge that builds up between them. This is known as electric potential energy. This energy has the potential to be transferred. There are two theories that describe the transformation. One such theory is the conventional current which was created by Benjamin Franklin. This is the model of positive current flow which states that electrons move from the positive (+) terminal, through the circuit, to the negative (-) terminal. However, we know today that this theory is wrong but use it anyway because it is too late to change the way we regard energy flow. The correct theory is known as electron flow which accurately states that electrons move from the negative (-) terminal, through the circuit, to the positive (+) terminal. In a battery the current flows in a single direction from the power supply through the conductor to the load (which uses the energy) and back to the power supply defined as direct current as opposed to the current continually changing directions defined as alternating current. Anyway in the end all this electric energy that is constantly flowing is converted into electrical energy.
The current can be measured by using this general formula :
I = charge (Q)
-----------
time (t)
I= Current in amperes
Because the size of an electron is very minute (2.82 x 1015 m )
scientists decided to measure electron in groups referred to as couloumbs. One coulomb is 6.25 x 1018
electrons.
Lets looks at batteries. You start off with chemical energy which separates the electrons from the atoms. As they continue to separate, there is a charge that builds up between them. This is known as electric potential energy. This energy has the potential to be transferred. There are two theories that describe the transformation. One such theory is the conventional current which was created by Benjamin Franklin. This is the model of positive current flow which states that electrons move from the positive (+) terminal, through the circuit, to the negative (-) terminal. However, we know today that this theory is wrong but use it anyway because it is too late to change the way we regard energy flow. The correct theory is known as electron flow which accurately states that electrons move from the negative (-) terminal, through the circuit, to the positive (+) terminal. In a battery the current flows in a single direction from the power supply through the conductor to the load (which uses the energy) and back to the power supply defined as direct current as opposed to the current continually changing directions defined as alternating current. Anyway in the end all this electric energy that is constantly flowing is converted into electrical energy.
 |
| Current Flow Theory |
 |
| Electron Flow Theory |
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