Friday, October 31, 2008
Thursday, October 30, 2008 - Blocks 1 & 3
Collected RA 4.2
Reviewed video on Newton's 2nd Law
Factors affecting air resistance:
1) speed
2) cross sectional area
Class Lab - What Factors Affect Contact Friction
Asked class for possible variables
Tested each variable
Factors affecting friction:
1) Normal Force
2) Surface Texture
Factors that did not have a significant effect
speed, contact area
A plot of Friction force vs Weight (Normal Force) shows a linear relationship. The slope, usually given by m (as in y = m*x + b)is instead given the Greek letter m, mu, and is called the coefficient of friction. This depends only on the surfaces and removes the effect of the normal force. We get an experimentally derived relationship
Ff = mu * Fn
There are two types of contact friction, static when the objects are at rest and kinetic when there is relative motion between the surfaces. The static friction force can range from zero to some maximum value. The kinetic friction force is constant. The maximum value of the static friction force is greater than or equal to the kinetic friction force showing that it is harder to get something going than to keep it going.
Reviewed video on Newton's 2nd Law
Factors affecting air resistance:
1) speed
2) cross sectional area
Class Lab - What Factors Affect Contact Friction
Asked class for possible variables
Tested each variable
Factors affecting friction:
1) Normal Force
2) Surface Texture
Factors that did not have a significant effect
speed, contact area
A plot of Friction force vs Weight (Normal Force) shows a linear relationship. The slope, usually given by m (as in y = m*x + b)is instead given the Greek letter m, mu, and is called the coefficient of friction. This depends only on the surfaces and removes the effect of the normal force. We get an experimentally derived relationship
Ff = mu * Fn
There are two types of contact friction, static when the objects are at rest and kinetic when there is relative motion between the surfaces. The static friction force can range from zero to some maximum value. The kinetic friction force is constant. The maximum value of the static friction force is greater than or equal to the kinetic friction force showing that it is harder to get something going than to keep it going.
Wednesday, October 29, 2008
Wednesday, October 29, 2008 - Blocks 1 and 3
Collected homework sheets on analytic solution to tension problems.
Quiz on analytic solution to tension problems.
Watched Hewitt video on Newton's Second Law paying particular attention to why heavy and light objects fall at the same rate.
In block 1 we got through the part on air resistance but I couldn't find RA 4.2 to hand out. In block 3 we did not get to air resistance but I did give out RA 4.2 for homework.
Quiz on analytic solution to tension problems.
Watched Hewitt video on Newton's Second Law paying particular attention to why heavy and light objects fall at the same rate.
In block 1 we got through the part on air resistance but I couldn't find RA 4.2 to hand out. In block 3 we did not get to air resistance but I did give out RA 4.2 for homework.
Tuesday, October 28, 2008
Tuesday, October 28, 2008 - Blocks 1 and 3
Handed back Inertia Quiz, Statics Lab, Worksheet on graphical solution to tension problems.
Quiz on graphical solution to tension problems
Talked about the difference between tension and net force
Analytic solution to tension problems
Did several examples: full problem, horz string, same angle, straight down, impossible
Handed out worksheet on analytic solution to tension problems. Due tomorrow
Quiz on graphical solution to tension problems
Talked about the difference between tension and net force
Analytic solution to tension problems
Did several examples: full problem, horz string, same angle, straight down, impossible
Handed out worksheet on analytic solution to tension problems. Due tomorrow
Thursday, October 23, 2008
Thursday, Oct 23, 2008 - Block 3
Went around room asking student what they told their parents about the inertia labs.
Talked about the various labs and explained them in terms of inertia.
Handed back RA 4.1 and went over it.
Show demo of compressing spine and why you are taller in the morning.
A force is simply a push or a pull.
Explained what is meant by a net force - vector sum of all forces acting on an object.
Introduced Newton's First Law of Motion: If there is no net external force acting on an object, an object at rest remains at rest and an object in motion keeps moving in a straight line with constant speed.
"Straight line with constant speed" means constant velocity.
Constant velocity means NO NET FORCE.
Mass, measured in kg, is a measure of inertia. If you toss an object back and forth from hand to hand you are measuring its inertia, how hard or easy it is to change its state of motion.
Volume and weight are NOT the same as mass.
Weight, measured in Newtons, is the force of gravity on an object. If you hold an object in your hand, you are measuring its weight.
A mass of 1 kg weights 10 N at the surface of the Earth. (Show with mass and spring balance.)
A mass of 1 kg also weighs about 2.2 lbs on Earth. One Newton is about the same as 0.22 lbs (A mass of 1 kg weighs 2.2 lbs) 0.22 lbs ~ 0.25 lbs. Therefore, instead of ordering a quarter pounder, you could order a Newtonburger.
Normal is a mathematical term meaning perpendicular to a surface. A normal force, which you have only with a surface (NOT strings) is the force perpendicular to that surface. Do NOT just include a normal force in all problems. There has to be a surface.
Introduced the idea of free-body diagrams. Isolate an object and show only the external forces that act on that object. You do NOT show velocity vectors, etc. or any forces that that object exerts on something else. Did a few examples of drawing free body diagrams.
Students worked on Free-Body Diagram worksheet and then we went over it in class.
Talked about the various labs and explained them in terms of inertia.
Handed back RA 4.1 and went over it.
Show demo of compressing spine and why you are taller in the morning.
A force is simply a push or a pull.
Explained what is meant by a net force - vector sum of all forces acting on an object.
Introduced Newton's First Law of Motion: If there is no net external force acting on an object, an object at rest remains at rest and an object in motion keeps moving in a straight line with constant speed.
"Straight line with constant speed" means constant velocity.
Constant velocity means NO NET FORCE.
Mass, measured in kg, is a measure of inertia. If you toss an object back and forth from hand to hand you are measuring its inertia, how hard or easy it is to change its state of motion.
Volume and weight are NOT the same as mass.
Weight, measured in Newtons, is the force of gravity on an object. If you hold an object in your hand, you are measuring its weight.
A mass of 1 kg weights 10 N at the surface of the Earth. (Show with mass and spring balance.)
A mass of 1 kg also weighs about 2.2 lbs on Earth. One Newton is about the same as 0.22 lbs (A mass of 1 kg weighs 2.2 lbs) 0.22 lbs ~ 0.25 lbs. Therefore, instead of ordering a quarter pounder, you could order a Newtonburger.
Normal is a mathematical term meaning perpendicular to a surface. A normal force, which you have only with a surface (NOT strings) is the force perpendicular to that surface. Do NOT just include a normal force in all problems. There has to be a surface.
Introduced the idea of free-body diagrams. Isolate an object and show only the external forces that act on that object. You do NOT show velocity vectors, etc. or any forces that that object exerts on something else. Did a few examples of drawing free body diagrams.
Students worked on Free-Body Diagram worksheet and then we went over it in class.
Thursday, Oct 23, 2008 - Block 1
Went around room asking student what they told their parents about the inertia labs.
Talked about the various labs and explained them in terms of inertia.
Handed back RA 4.1 and went over it.
Show demo of compressing spine and why you are taller in the morning.
A force is simply a push or a pull.
Explained what is meant by a net force - vector sum of all forces acting on an object.
Introduced Newton's First Law of Motion: If there is no net external force acting on an object, an object at rest remains at rest and an object in motion keeps moving in a straight line with constant speed.
"Straight line with constant speed" means constant velocity.
Constant velocity means NO NET FORCE.
Mass, measured in kg, is a measure of inertia. If you toss an object back and forth from hand to hand you are measuring its inertia, how hard or easy it is to change its state of motion.
Volume and weight are NOT the same as mass.
Weight, measured in Newtons, is the force of gravity on an object. If you hold an object in your hand, you are measuring its weight.
A mass of 1 kg weights 10 N at the surface of the Earth. (Show with mass and spring balance.)
A mass of 1 kg also weighs about 2.2 lbs on Earth. One Newton is about the same as 0.22 lbs (A mass of 1 kg weighs 2.2 lbs) 0.22 lbs ~ 0.25 lbs. Therefore, instead of ordering a quarter pounder, you could order a Newtonburger.
Normal is a mathematical term meaning perpendicular to a surface. A normal force, which you have only with a surface (NOT strings) is the force perpendicular to that surface. Do NOT just include a normal force in all problems. There has to be a surface.
Introduced the idea of free-body diagrams. Isolate an object and show only the external forces that act on that object. You do NOT show velocity vectors, etc. or any forces that that object exerts on something else. Did a few examples of drawing free body diagrams.
Homework sheet Newton's Laws worksheet.
Talked about the various labs and explained them in terms of inertia.
Handed back RA 4.1 and went over it.
Show demo of compressing spine and why you are taller in the morning.
A force is simply a push or a pull.
Explained what is meant by a net force - vector sum of all forces acting on an object.
Introduced Newton's First Law of Motion: If there is no net external force acting on an object, an object at rest remains at rest and an object in motion keeps moving in a straight line with constant speed.
"Straight line with constant speed" means constant velocity.
Constant velocity means NO NET FORCE.
Mass, measured in kg, is a measure of inertia. If you toss an object back and forth from hand to hand you are measuring its inertia, how hard or easy it is to change its state of motion.
Volume and weight are NOT the same as mass.
Weight, measured in Newtons, is the force of gravity on an object. If you hold an object in your hand, you are measuring its weight.
A mass of 1 kg weights 10 N at the surface of the Earth. (Show with mass and spring balance.)
A mass of 1 kg also weighs about 2.2 lbs on Earth. One Newton is about the same as 0.22 lbs (A mass of 1 kg weighs 2.2 lbs) 0.22 lbs ~ 0.25 lbs. Therefore, instead of ordering a quarter pounder, you could order a Newtonburger.
Normal is a mathematical term meaning perpendicular to a surface. A normal force, which you have only with a surface (NOT strings) is the force perpendicular to that surface. Do NOT just include a normal force in all problems. There has to be a surface.
Introduced the idea of free-body diagrams. Isolate an object and show only the external forces that act on that object. You do NOT show velocity vectors, etc. or any forces that that object exerts on something else. Did a few examples of drawing free body diagrams.
Homework sheet Newton's Laws worksheet.
Wednesday, Oct 22, 2008 - Blocks 1 and 3
Collected RA 4.1
Went over Vector and Projectile Motion Test
Today we are starting a new unit. We are going to learns the ways of S I N (Sir Isaac Newton)
Introduced idea of inertia. How many people slept in over the 4-day weekend. If you did you were practicing good physics. An object at rest tends to stay at rest. You were exhibiting Galileo's idea of inertia which is so important it is Newton's First Law of Motion - the Law of Inertia.
An object at rest tends to stay at rest and an object in motion tends to keep moving in a straight line at constant speed unless acted on by an outside force.
Today you weren't able to sleep. An outside force acted on you to change your state of motion. Often this force is F = ma (your mother). But that's Newton's second law which will come a bit later.
Demos with railway tie. Showed inertia mini-lab demos. Students did mini-labs.
Homework - tell parents about what you did in class today and relate it to inertia.
Went over Vector and Projectile Motion Test
Today we are starting a new unit. We are going to learns the ways of S I N (Sir Isaac Newton)
Introduced idea of inertia. How many people slept in over the 4-day weekend. If you did you were practicing good physics. An object at rest tends to stay at rest. You were exhibiting Galileo's idea of inertia which is so important it is Newton's First Law of Motion - the Law of Inertia.
An object at rest tends to stay at rest and an object in motion tends to keep moving in a straight line at constant speed unless acted on by an outside force.
Today you weren't able to sleep. An outside force acted on you to change your state of motion. Often this force is F = ma (your mother). But that's Newton's second law which will come a bit later.
Demos with railway tie. Showed inertia mini-lab demos. Students did mini-labs.
Homework - tell parents about what you did in class today and relate it to inertia.
Tuesday, Oct 21, 2008 - Blocks 1 and 3
Test on Vectors and Projectile Motion.
Students picked up RA 4.1 due on Wednesday.
Students picked up RA 4.1 due on Wednesday.
Monday, October 20, 2008
Monday, October 20, 2008 - Blocks 1 and 3
After a few questions, it was clear the students needed more time to review for tomorrow's test instead of starting the new material.
I answered questions at the board and individual questions one-on-one.
Test is tomorrow.
I answered questions at the board and individual questions one-on-one.
Test is tomorrow.
Wednesday, October 15, 2008
Wednesday, Oct 15, 2008 - Blocks 1 and 3
Showed Hit the Bar video.
Went over end of chapter questions. Expanded them to include finding launch angle and speeds and angles at various points in the trajectory.
When finding launch angle, you have to use the velocities, NOT the height and range distances.
Talked about test.
Gave Projectile Rocket Quiz 2 (IB)
Block 3 also did retake for uncertainty quiz
Offered extra credit for students attending the Saturday lecture at PSU on Our Cosmis Context.
Time: 10 am, Saturday, Oct 18
Place: Hoffman Hall PSU
To get credit, bring a brief outline of what you found interesting or bring a picture of you with Dr. Todd Duncan.
Went over end of chapter questions. Expanded them to include finding launch angle and speeds and angles at various points in the trajectory.
When finding launch angle, you have to use the velocities, NOT the height and range distances.
Talked about test.
Gave Projectile Rocket Quiz 2 (IB)
Block 3 also did retake for uncertainty quiz
Offered extra credit for students attending the Saturday lecture at PSU on Our Cosmis Context.
Time: 10 am, Saturday, Oct 18
Place: Hoffman Hall PSU
To get credit, bring a brief outline of what you found interesting or bring a picture of you with Dr. Todd Duncan.
Tuesday, Oct 14, 2008 - Blocks 1 and 3
Went over problems in relative velocity. Showed how to use it for airplanes landing and taking off, and for the raindrop on windshield problem.
Gave quizzes on Gen Phys Rocket Projectile Motion, and Rocket Trajectory.
In Block 3, also gave Physical Science Math Skills Quizzes 1 and 2.
Students counted off by 4 and worked on end of chapter 3 questions, exercises, problems.
Gave quizzes on Gen Phys Rocket Projectile Motion, and Rocket Trajectory.
In Block 3, also gave Physical Science Math Skills Quizzes 1 and 2.
Students counted off by 4 and worked on end of chapter 3 questions, exercises, problems.
Monday, Oct 13, 2008 - Blocks 1 and 3
Covered relative velocity.
Did several examples. Handed out vector worksheet 6 on relative velocity which students did in class.
Did several examples. Handed out vector worksheet 6 on relative velocity which students did in class.
Wednesday, October 8, 2008
Thursday, Oct 9, 2008 - Blocks 1 and 3
Hit the Bar Lab!!
Write-ups for those who missed are due on Tuesday.
Write-ups for those who missed are due on Tuesday.
Tuesday, October 7, 2008
Wednesday, October 8, 2008 - Blocks 1 and 3
Quiz 3 on graphical addition of vectors. I'll keep the best 2.
Quiz on analytic addition of vectors.
Finish going over Hit the Bar Lab competition 3.
Magic Tube demo.
Ballistic Cart demo.
Quiz on analytic addition of vectors.
Finish going over Hit the Bar Lab competition 3.
Magic Tube demo.
Ballistic Cart demo.
Tuesday, Oct 7, 2008 - Blocks 1 and 3
Collected Rocket 2 labs.
Students are still not doing well on the graphical addition of vector quizzes and on the analytic addition of vectors (vector worksheet 4).
I went over in detail an example of graphical addition of vectors and did the same example in detail for analytic addition of vectors.
Handed back quizzes and vector worksheet 4. Also handed back CD 3.2
Asked if any questions on Rocket Lab or on the homework problems 17-25
Students did vector worksheet 5 on ijk notation.
Explained set-up for Hit the Bar Lab and went through competitions 1 and 2. Didn't get through competition 3. Left the details for homework - find distance ball falls from max height, time to fall, total time in air, x location.
Students are still not doing well on the graphical addition of vector quizzes and on the analytic addition of vectors (vector worksheet 4).
I went over in detail an example of graphical addition of vectors and did the same example in detail for analytic addition of vectors.
Handed back quizzes and vector worksheet 4. Also handed back CD 3.2
Asked if any questions on Rocket Lab or on the homework problems 17-25
Students did vector worksheet 5 on ijk notation.
Explained set-up for Hit the Bar Lab and went through competitions 1 and 2. Didn't get through competition 3. Left the details for homework - find distance ball falls from max height, time to fall, total time in air, x location.
Monday, October 6, 2008
Monday, Oct 6, 2008 - Blocks 1 and 3
Handed back quizzes on Graphical Addition of Vectors.
Also handed back Vector Worksheet 4 and redos for CD 3.2
Asked if there were any questions.
Asked students to measure in metric units (cm) and NOT inches.
Gave another quiz on Graphical Addition of Vectors.
Showed rest of Hewitt video on Vectors and Projectile Motion.
At end of class, gave students time to complete CD 3.2, Vector Worksheet 4, or work on homework problems 17-25.
Also handed back Vector Worksheet 4 and redos for CD 3.2
Asked if there were any questions.
Asked students to measure in metric units (cm) and NOT inches.
Gave another quiz on Graphical Addition of Vectors.
Showed rest of Hewitt video on Vectors and Projectile Motion.
At end of class, gave students time to complete CD 3.2, Vector Worksheet 4, or work on homework problems 17-25.
Friday, October 3, 2008
Friday, October 3, 2008 - Blocks 1 and 3
Collected Vector Worksheet 4
Gave Graphical Addition of Vector Quiz
Graded Vector Worksheet 4 while students took quiz
Handed back Vector Worksheet 4. If students got it all right, then I entered it in my gradebook. If students had errors, I asked them to correct errors and hand back. Those students who did not hand it in must hand it in Monday but don't get the second chance.
Went over Graphical Addition of Vector Quiz.
If students had problems, another quiz on Monday on graphical addition of vectors.
Did example of shooting a rocket straight up (launch angle 90 deg) and hitting the ground after 8 seconds.
Re-did example, same rocket, SAME LAUNCH SPEED, but with a launch angle of 60 deg. Found vix, viy, tup, tdown, total time in air, range.
Students re-did example with launch angle of 45 deg.
Did another example of shooting a rocket off at some angle and having it hit 100 m down range after 5.2 seconds.
Found vix, viy, launch speed, launch angle, height
In block 1 handed out problem set and asked students to do problems 17-25.
Many had difficulties so in block 3 I did the problem of object shot horizontally off cliff 37 m high and landing 77 m away. Found launch velocity, time in air, vy hit, and hitting speed.
Asked Block 3 to omit prob 22
Gave Graphical Addition of Vector Quiz
Graded Vector Worksheet 4 while students took quiz
Handed back Vector Worksheet 4. If students got it all right, then I entered it in my gradebook. If students had errors, I asked them to correct errors and hand back. Those students who did not hand it in must hand it in Monday but don't get the second chance.
Went over Graphical Addition of Vector Quiz.
If students had problems, another quiz on Monday on graphical addition of vectors.
Did example of shooting a rocket straight up (launch angle 90 deg) and hitting the ground after 8 seconds.
Re-did example, same rocket, SAME LAUNCH SPEED, but with a launch angle of 60 deg. Found vix, viy, tup, tdown, total time in air, range.
Students re-did example with launch angle of 45 deg.
Did another example of shooting a rocket off at some angle and having it hit 100 m down range after 5.2 seconds.
Found vix, viy, launch speed, launch angle, height
In block 1 handed out problem set and asked students to do problems 17-25.
Many had difficulties so in block 3 I did the problem of object shot horizontally off cliff 37 m high and landing 77 m away. Found launch velocity, time in air, vy hit, and hitting speed.
Asked Block 3 to omit prob 22
Thursday, October 2, 2008
Thursday, Oct 2, 2008 - Blocks 1 and 3
Showed rocket video
Went over vector worksheet 2
Students did vector worksheet 3 - went over it in class
Handed out problem solving strategy for analytic vector addition
Handed out vector worksheet 4 - students started it in class, finish for homework.
Went over vector worksheet 2
Students did vector worksheet 3 - went over it in class
Handed out problem solving strategy for analytic vector addition
Handed out vector worksheet 4 - students started it in class, finish for homework.
Wednesday, October 1, 2008
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