Wednesday, February 25, 2009
Wednesday Lesson
Y11HW Summarize Chapter 10 - 1 Page. Prepare for Prac 10.1 on page 221 with book ruled up
We will look at Vector components and acceleration using Tracker. You can download it from R drive, science, yr10, physics. It will greatly assist in performing pracs
Turn vectors into scalar (projections) then back into vectors.
- Each V has projections Vxx and Vyy where x and y "Unit vectors along the axis"
Newtons Laws 1-2-3
N1 Straight line, constant velocity (Speed and Direction), if F = 0
Historical: Break with Archemedies and common sense.
Application: Cars thrown through the window
N2 Sum of Forces = Resultant Force = Mass x Acceleration. (on a body)
Historical: Invention of Mass a number to link Force (that can be felt) and acceleration (that can be seen)
Application: Anything that moves, Constant velocity means NET force is zero.
Types of Forces
Internal- Generated by a Field generated by a body at distance Force just dropped on to object. - Gravity
External - Generated by contact , two forces generated. In sum only add the forces acting on it. Strings and Friction
N3 Every force has an equal and opposite force. (in a system)
Historical: Invention of Momentum, Impulse fT or Ft, ease up or death.
Application: Collisions, Lethal force
Friday, February 20, 2009
Homework
Due Friday homework was set upto Q20 Page 190
Homework now complete to Q25
In Class we cover Q 20 and how the area under a VT curve is the displacement , the gradient is the acceleration.
We are now in a position to Revise Newtons 3 Laws:
N1: With no forces, their velocity is unchanged.
This is historical reference to the different ideas of Aristotle of Violent, and curved motion.
N2: Sum of forces = product of acceleration and mass
Here the idea of forces need to be developed. Internal forces are found the product of an external field and an objects field force factor. For gravity the field is described by g and the number inserted to create the force is the Mass. In this case we draw the force on the object, determined by the field direction and the size by the size of the field and multiplier factor. The are also external forces mostly generated by strings or by contact with surfaces. Here we draw pairs of forces at the point of contact.
The sum of forces = a resultant force, ie a single force that does not add up. and this is the acceleration.
N3 F12=-F21 for every force there is an equal and opposite force. In the case of internal forces where the force vector is inserted, there is an opposite force but it is just not on the diagram. For contact forces we draw a pair of forces that cancel. This law basically leads to the concepts of momentum transfere, and the conservation of momentum as the forces balance.
Homework now complete to Q25
In Class we cover Q 20 and how the area under a VT curve is the displacement , the gradient is the acceleration.
We are now in a position to Revise Newtons 3 Laws:
N1: With no forces, their velocity is unchanged.
This is historical reference to the different ideas of Aristotle of Violent, and curved motion.
N2: Sum of forces = product of acceleration and mass
Here the idea of forces need to be developed. Internal forces are found the product of an external field and an objects field force factor. For gravity the field is described by g and the number inserted to create the force is the Mass. In this case we draw the force on the object, determined by the field direction and the size by the size of the field and multiplier factor. The are also external forces mostly generated by strings or by contact with surfaces. Here we draw pairs of forces at the point of contact.
The sum of forces = a resultant force, ie a single force that does not add up. and this is the acceleration.
N3 F12=-F21 for every force there is an equal and opposite force. In the case of internal forces where the force vector is inserted, there is an opposite force but it is just not on the diagram. For contact forces we draw a pair of forces that cancel. This law basically leads to the concepts of momentum transfere, and the conservation of momentum as the forces balance.
Friday, February 13, 2009
Friday Lesson
Found text book on Ebhigh.com
Did intital Moodle- test and discussion on assignment.
Homework - Q8,Q9,Q10.
Did intital Moodle- test and discussion on assignment.
Homework - Q8,Q9,Q10.
Thursday, February 12, 2009
More Vector Maths
Last lesson we considered a snail moving slowly North for 1s and quickly West for 1s
Here is a good interative site
This lesson we will take a fast and slow ticker tape, the slow represents current that travels N, S,W,E and you will have to find the Vector necessary to travel N.
We will reveiw Q5 on page 194 Jacaranda and set Q6 for homework.
Here is a good interative site
This lesson we will take a fast and slow ticker tape, the slow represents current that travels N, S,W,E and you will have to find the Vector necessary to travel N.
We will reveiw Q5 on page 194 Jacaranda and set Q6 for homework.
Monday, February 2, 2009
Vector maths
Adding vectors is done by:
1) Drawing the vectors
2) breaking into X an Y components, adding Scalars, and recombining answers.
A good site with worked solutions for vector subtraction is site
1) Drawing the vectors
2) breaking into X an Y components, adding Scalars, and recombining answers.
A good site with worked solutions for vector subtraction is site
Homework
Jacaranda Page 194 Questions 1 -5
distance- is between point a and b is the length of path pulled out straight(depending on the path)
= to a magnitude and unit this is a SCALAR
Displacement: is the chance in place as the "crow's flys"
= to a magnitude, unit, and direction this is VECTOR
it is draw in the diagram with an arrow. the Head is where it finishes, the tail is where it begins.
It is drawn to scale, and direction.( Diagram now needs a compass or an up)
The unit and magnitude is written half way along.
Vector addition is more complex than Scalar.....
Exercise Draw the Vector C , A+B =C
A is 8 paces north, B is 6 paces west.
Exercise Vector D Sum of ( 3 m North, 5 m East, 5 m South, 7 m West)
Exercise Vector E (Sum 7 m West, 5m South, 3 m North, 5 m East)
How do you subtract vectors? ANS go the opposite way
Exercise what is A - B ? Hint A + (-B).
distance- is between point a and b is the length of path pulled out straight(depending on the path)
= to a magnitude and unit this is a SCALAR
Displacement: is the chance in place as the "crow's flys"
= to a magnitude, unit, and direction this is VECTOR
it is draw in the diagram with an arrow. the Head is where it finishes, the tail is where it begins.
It is drawn to scale, and direction.( Diagram now needs a compass or an up)
The unit and magnitude is written half way along.
Vector addition is more complex than Scalar.....
Exercise Draw the Vector C , A+B =C
A is 8 paces north, B is 6 paces west.
Exercise Vector D Sum of ( 3 m North, 5 m East, 5 m South, 7 m West)
Exercise Vector E (Sum 7 m West, 5m South, 3 m North, 5 m East)
How do you subtract vectors? ANS go the opposite way
Exercise what is A - B ? Hint A + (-B).
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About Me
- drhill
- I come from a Science family: My father Geoffrey Hill was Australia's first computer programmer on CSIRAC the fourth computer in the world. He is credited with invention of Computer music and the development of “Interprogram” a language before Basic. My PhD is in Atomic and Molecular Physics. I have researched the activated oxygen layer above the ozone layer, and 'Assigned' the world's smallest molecule. At the University of Toronto I researched high power UV lasers. I have specialized in automation in fibre optics. This developed into research in Machine Intellect and Robots. I have enjoyed work as an Explainer with Questacon and my time as a part-time soldier. I currently teach High School Science at Epping Boys’ High.