Collect RA 5.2
Show parts of video dealing with railroad cars.
Momentum Quiz
Intro to conservation of momentum: If no net external force acts on the system, then there is no change in momentum.
Conservation of Momentum has never been shown to fail. It does not apply in cases in which there is an external force, such as dropping an object.
Applied Conservation of Momentum to collisions.
Two basic types of collisions:
1. Elastic (Things bounce)
2. Inelastic (Things stick)
If there is no net external force, momentum is conserved in both types of collisions.
Demos with air track for both types of collisions.
Worked inelastic collision problems on board showing problems solving strategy.
Students worked on and handed in Elastic Collision Worksheet.
Homework: RA 5.3, CD chapt 5
Monday, April 27, 2009
Monday, April 27, 2009 - Block 2
Go over Newton's 3rd Law Test
Collected, graded, and went over RA 5.1
Demo with blowpipes and marshmallows to show that longer cannons impart more impulse (same force, longer time) than short cannons.
Demo with force plate. Much larger force when lock knees. The impulse is the same but the time to stop is shorter. If the force varies, you can find the impulse by finding the area under the curve.
Rebounding increases impulse.
Demo with happy/sad balls knocking down block.
Homework: RA 5.2
Collected, graded, and went over RA 5.1
Demo with blowpipes and marshmallows to show that longer cannons impart more impulse (same force, longer time) than short cannons.
Demo with force plate. Much larger force when lock knees. The impulse is the same but the time to stop is shorter. If the force varies, you can find the impulse by finding the area under the curve.
Rebounding increases impulse.
Demo with happy/sad balls knocking down block.
Homework: RA 5.2
Friday, April 24, 2009 - Block 2
Did not have time to grade Newton's 3rd Law test so did not go over it.
Intro to Impulse and Momentum.
Impulse = Fnet * t
Units of impulse are N s
Momentum = ooomph = mass * velocity
Derived Impulse = Change in momentum
Several examples
Egg toss lab
Handed out RA 5.1. Students had 10 min in class to work on assignment - finish for homework.
Intro to Impulse and Momentum.
Impulse = Fnet * t
Units of impulse are N s
Momentum = ooomph = mass * velocity
Derived Impulse = Change in momentum
Several examples
Egg toss lab
Handed out RA 5.1. Students had 10 min in class to work on assignment - finish for homework.
Thursday, April 23, 2009 - Block 2
Newton's 3rd Law Test
Did not give reading assignment for next unit.
Did not give reading assignment for next unit.
Tuesday, April 21, 2009 - Block 2
Reviewed for test.
Went over end of chapter questions
Did several problems from problem worksheet
Handed out CD 5.2 for practice
No School on Wednesday, Test on Thursday
Went over end of chapter questions
Did several problems from problem worksheet
Handed out CD 5.2 for practice
No School on Wednesday, Test on Thursday
Monday, April 20, 2009 - Block 2
Went over problems from worksheet in class.
Did my problems from front of worksheet, except for problem 1.
Assigned inclined plane problems and ball problem for HW.
Did my problems from front of worksheet, except for problem 1.
Assigned inclined plane problems and ball problem for HW.
Friday, April 17, 2009
Friday, April 17, 2009 - Block 2
Collected RA 4.5
Hung pictures on board and students voted on Horse Sense
Went over RA 4.4
Talked about what force a bathroom scale actually reads (It reads the reaction to normal force of person on scale. Did examples of bathroom scale in elevator showing how you draw the free body diagram, choose the direction of acceleration to be positive, write down Newton's Law and solve for the normal force (which has the same magnitude as the scale reading).
Asked students to predict what a Force vs Time diagram would be for someone stepping on the force plate, jumping up and coming down, and then stepping off. After discussion the predictions on board, students did demo.
On Applying Newton's Laws worksheet, asked students to do the blocks problem. Explained it in detail on the board.
Homework, do circled problems 3-24 for Monday. Gave students 15 minutes in class to work on them. Test is Thursday.
Hung pictures on board and students voted on Horse Sense
Went over RA 4.4
Talked about what force a bathroom scale actually reads (It reads the reaction to normal force of person on scale. Did examples of bathroom scale in elevator showing how you draw the free body diagram, choose the direction of acceleration to be positive, write down Newton's Law and solve for the normal force (which has the same magnitude as the scale reading).
Asked students to predict what a Force vs Time diagram would be for someone stepping on the force plate, jumping up and coming down, and then stepping off. After discussion the predictions on board, students did demo.
On Applying Newton's Laws worksheet, asked students to do the blocks problem. Explained it in detail on the board.
Homework, do circled problems 3-24 for Monday. Gave students 15 minutes in class to work on them. Test is Thursday.
Thursday, April 16, 2009
Thursday, April 16, 2009 - Block 2
Collected RA 4.4
Reviewed Newton's 3rd Law
Explained problem of boxer hitting paper - Can he exert a force of 200 N on paper? Showed using F = m*a that it was not possible if paper hung in air, but would be possible if paper was against a wall.
To examine the magnitude of the force, look what happens. When hit at the same speed, the "free paper" accelerated and the fist carried through. Not enough force of paper on fist to stop the fist. When against the wall, the paper exerts enough force on the fist the stop the fist. If the paper exerted an even greater force, the fist might rebound.
Showed video clip from Independence Day. Hollywood does not understand the 3rd Law.
Example of flies in a jar.
Helicopter on force plate.
Handed out RA 4.5 due tomorrow.
Handed out CD 6.1 due for last time on Monday. Explained that I wanted not just arrows but descriptions of the forces written in the margins for the last problem on the front side.
Reviewed Newton's 3rd Law
Explained problem of boxer hitting paper - Can he exert a force of 200 N on paper? Showed using F = m*a that it was not possible if paper hung in air, but would be possible if paper was against a wall.
To examine the magnitude of the force, look what happens. When hit at the same speed, the "free paper" accelerated and the fist carried through. Not enough force of paper on fist to stop the fist. When against the wall, the paper exerts enough force on the fist the stop the fist. If the paper exerted an even greater force, the fist might rebound.
Showed video clip from Independence Day. Hollywood does not understand the 3rd Law.
Example of flies in a jar.
Helicopter on force plate.
Handed out RA 4.5 due tomorrow.
Handed out CD 6.1 due for last time on Monday. Explained that I wanted not just arrows but descriptions of the forces written in the margins for the last problem on the front side.
Wednesday, April 15, 2009 - Block 2
Newton's 3rd Law lecture with demos.
Included magic tube.
Handed out RA 4.4 due tomorrow. Students had about 15 minutes to work on it in class.
Included magic tube.
Handed out RA 4.4 due tomorrow. Students had about 15 minutes to work on it in class.
Tuesday, April 14, 2009 - Block 2
Handed back and went over Air Resistance Lab
Went over test
Handed out Applying Newton's Laws Worksheet
Showed part of Physics Extravaganza video
Went over test
Handed out Applying Newton's Laws Worksheet
Showed part of Physics Extravaganza video
Tuesday, April 14, 2009
Thursday, April 9, 2009
Thursday, April 9, 2009 - Block 2
Went around room asking students what they thought would be on the test.
Elaborated on their answers and answered any questions.
Assigned problems 4,5,8 at end of chapter. Went over them.
Went over some end of chapter questions.
Gave students time in class to work on problems from the two worksheets while I graded CD 5.1. Unfortunately handed back CD 5.1 before entering grades. Students wanted it to study by so I told them hand them back in tomorrow.
Test tomorrow.
Elaborated on their answers and answered any questions.
Assigned problems 4,5,8 at end of chapter. Went over them.
Went over some end of chapter questions.
Gave students time in class to work on problems from the two worksheets while I graded CD 5.1. Unfortunately handed back CD 5.1 before entering grades. Students wanted it to study by so I told them hand them back in tomorrow.
Test tomorrow.
Wednesday, April 8, 2009
Wednesday, April 8, 2009 - Block 2
Practice quiz on Newton's 2nd Law including coefficient of friction. Did not collect quizzes.
Handed out Problems in Newton's Laws problem sheet. Gave students time to work on it in class. Went over problem 11 with car in mud and explained how this worked with my fallen cedar tree.
Graded CD 5.1 while students worked on problems. Handed back graded sheets for correction.
Handed out worksheet on coefficients of friction. Did problem 5. Showed how pushing or pulling up decreases the normal force which then decreases the friction force. Related it to football.
Asked students to bring textbooks to class tomorrow.
Handed out Problems in Newton's Laws problem sheet. Gave students time to work on it in class. Went over problem 11 with car in mud and explained how this worked with my fallen cedar tree.
Graded CD 5.1 while students worked on problems. Handed back graded sheets for correction.
Handed out worksheet on coefficients of friction. Did problem 5. Showed how pushing or pulling up decreases the normal force which then decreases the friction force. Related it to football.
Asked students to bring textbooks to class tomorrow.
Tuesday, April 7, 2009
Tuesday, April 7, 2009 - Block 2
Collected Air Resistance Labs
Reviewed Friction lab in detail. Reviewed the concept of coefficient of friction.
Compared factors affecting contact friction to factors affecting air resistance.
Showed how to determine coefficients of friction by raising a board and seeing at what angle the object begins to slide and then at what angle it continues to slide with constant velocity.
Did a problem in calculating coefficient of friction and using the problem solving strategy for Newton's Laws problems.
Watched last part of Hewitt's 2nd law video, the part on air resistance.
Went outside and threw boomerangs for the last 15 minutes of class.
Reviewed Friction lab in detail. Reviewed the concept of coefficient of friction.
Compared factors affecting contact friction to factors affecting air resistance.
Showed how to determine coefficients of friction by raising a board and seeing at what angle the object begins to slide and then at what angle it continues to slide with constant velocity.
Did a problem in calculating coefficient of friction and using the problem solving strategy for Newton's Laws problems.
Watched last part of Hewitt's 2nd law video, the part on air resistance.
Went outside and threw boomerangs for the last 15 minutes of class.
Monday, April 6, 2009
Monday, April 6, 2009 - Block 2
Handed back Quiz on analytic statics, CD 4.2, RA 4.2, Newton's 2nd Law problem set
Gave students one more day to redo CD 4.2 since I forgot to hand them back on Friday due to the lab.
Went over RA 4.2
Friction Lab - How to do an IB lab.
Gave students one more day to redo CD 4.2 since I forgot to hand them back on Friday due to the lab.
Went over RA 4.2
Friction Lab - How to do an IB lab.
Friday, April 3, 2009 - Block 2
Talked about air resistance. Factors that affect air resistance are speed and cross-sectional area.
Discussed Air Resistance Lab.
For write-up I need the name, partner's name, name of lab, date.
Answers to Preliminary Questions. Tell me what it is you are answering in your answer.
Data table with labels and units including 3 trials for each number of filters, average terminal velocity and the square of the average terminal velocity.
Graphs: 2 graphs, VT vs number of filters and VT^2 vs number of filters. For the one that gives the best fit straight line through the origin, use the Linest function of Excel to find the slope and uncertainty in the slope.
Results:
1. Which graph gives the best fit straight line through the origin
2. Which model give the best fit, drag force = -bv, drag force = -c v^2
VT ~ mass, VT^2 ~ mass
3. Answer question 4 in analysis section.
Students worked in pairs to do the lab.
Discussed Air Resistance Lab.
For write-up I need the name, partner's name, name of lab, date.
Answers to Preliminary Questions. Tell me what it is you are answering in your answer.
Data table with labels and units including 3 trials for each number of filters, average terminal velocity and the square of the average terminal velocity.
Graphs: 2 graphs, VT vs number of filters and VT^2 vs number of filters. For the one that gives the best fit straight line through the origin, use the Linest function of Excel to find the slope and uncertainty in the slope.
Results:
1. Which graph gives the best fit straight line through the origin
2. Which model give the best fit, drag force = -bv, drag force = -c v^2
VT ~ mass, VT^2 ~ mass
3. Answer question 4 in analysis section.
Students worked in pairs to do the lab.
Thursday, April 2, 2009
Thursday, April 2, 2009 - Block 2
Handed back graphical statics quiz and CD 4.2
Collected RA 4.2
Students did analytic statics quiz.
Went over the quiz on the board.
Continued Hewitt 2nd Law video
Asked students why two objects of different weight fall at the same rate. For those students who said the forces were the same, I had them come to the front of the class and hold the bowling ball and tennis ball out in front of them so really show that the forces are not the same.
Re-explained it is the ratio of the force to mass that is the same. This is the second really big thing I want students to know. (The first was the reason why astronauts in the space shuttle appear to be weightless).
Handed out Newton's 2nd Law Problem worksheet. Gave students time in class to work on it. It is due tomorrow.
Collected RA 4.2
Students did analytic statics quiz.
Went over the quiz on the board.
Continued Hewitt 2nd Law video
Asked students why two objects of different weight fall at the same rate. For those students who said the forces were the same, I had them come to the front of the class and hold the bowling ball and tennis ball out in front of them so really show that the forces are not the same.
Re-explained it is the ratio of the force to mass that is the same. This is the second really big thing I want students to know. (The first was the reason why astronauts in the space shuttle appear to be weightless).
Handed out Newton's 2nd Law Problem worksheet. Gave students time in class to work on it. It is due tomorrow.
Wednesday, April 1, 2009
Wednesday, April 1, 2009 - Block 2
Quiz on Graphical Statics Problems
Went over Analytic Solution to Statics Problems
What happens if the forces don't balance out? If the net force does NOT equal zero?
Then the object changes the way it moves, it accelerates.
This is the biggie - Newton's 2nd Law
a = Fnet/mass
Demo with cart on ramp.
Draw free-body diagram.
Calculate the force of friction, calculate the angle. Check angle measurement. It works!!
Start Hewitt video on Newton's 2nd Law.
Hand out RA 4.2 - due tomorrow
Went over Analytic Solution to Statics Problems
What happens if the forces don't balance out? If the net force does NOT equal zero?
Then the object changes the way it moves, it accelerates.
This is the biggie - Newton's 2nd Law
a = Fnet/mass
Demo with cart on ramp.
Draw free-body diagram.
Calculate the force of friction, calculate the angle. Check angle measurement. It works!!
Start Hewitt video on Newton's 2nd Law.
Hand out RA 4.2 - due tomorrow
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