Quiz on 7 blocks both elastic and inelastic.
Went over quiz and varied it a bit for more practice.
Showed parts of the Hewitt video - those dealing with boxing and trains.
Went over problem questions from WebAssign.
Asked if there were any questions on the Momentum Problem worksheet. Many students had not done it so I let the students work and review on their own, going around and answering any questions.
Test tomorrow on impulse and momentum
Wednesday, April 30, 2008
Tuesday, April 29, 2008
Tuesday, April 29, 2008
Handed back Collision Lab.
Went over 7-block elastic collision problem - first the long way and then showing how to do it the easy way. Then did the problem assuming an inelastic collision - the important thing here is to check which blocks actually collide.
Went over RA 5.3
Ballistic Pendulum Lab/Demo/Calculation
Showed how to calculate impulse graphically for a non-constant force.
Gave students time in class to work on worksheet Problems in Momentum.
Assigned WebAssign Hewitt chapter 5 for review (due tomorrow)
Wednesday we will go over any questions on the problem sheet, any questions from WebAssign, and review for the test.
Test scheduled for Thursday.
Went over 7-block elastic collision problem - first the long way and then showing how to do it the easy way. Then did the problem assuming an inelastic collision - the important thing here is to check which blocks actually collide.
Went over RA 5.3
Ballistic Pendulum Lab/Demo/Calculation
Showed how to calculate impulse graphically for a non-constant force.
Gave students time in class to work on worksheet Problems in Momentum.
Assigned WebAssign Hewitt chapter 5 for review (due tomorrow)
Wednesday we will go over any questions on the problem sheet, any questions from WebAssign, and review for the test.
Test scheduled for Thursday.
Monday, April 28, 2008
Monday, April 28, 2008
Reviewed collisions and demos from Friday.
Collisions Lab
Bowling ball and golf ball competition.
Talked about slingshot effect and did problem.
Supernova demo.
Handed out Problems in Momentum worksheet and assigned 1,2 for tomorrow.
Collisions Lab
Bowling ball and golf ball competition.
Talked about slingshot effect and did problem.
Supernova demo.
Handed out Problems in Momentum worksheet and assigned 1,2 for tomorrow.
Friday, April 25, 2008
Friday, April 25, 2008
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.
Momentum Quiz
Demo with happy/sad balls knocking down block.
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
Demo with blowpipes and marshmallows to show that longer cannons impart more impulse (same force, longer time) than short cannons.
Momentum Quiz
Demo with happy/sad balls knocking down block.
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
Thursday, April 24, 2008
Thursday, April 24, 2008
Went over Newton's Laws test.
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
Force plate demo - flex knees, lock knees
Handed out RA 5.2. 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
Force plate demo - flex knees, lock knees
Handed out RA 5.2. Students had 10 min in class to work on assignment - finish for homework.
Tuesday, April 22, 2008
Tuesday, April 22, 2008
Newton's Laws Test on 2nd and 3rd laws.
RA 5.1 due Thursday.
No class on Wednesday
RA 5.1 due Thursday.
No class on Wednesday
Monday, April 21, 2008
Monday April 21, 2008
Reviewed some of the WebAssign problems that gave people trouble.
Andrew demonstrated jumping into the air.
Students predicted what a graph of normal force vs time would look like for his jump.
Discussed these graphs. Used force plate to observe the actual force vs time.
Talked about man on bathroom scale in elevator problems.
Suppose you have a jar of flies on an electronic balance and all the flies are sitting on the bottom. How would the scale reading change if the flies took off and flew around the jar. Referred to finger in water demo - the scale reading would not change.
Demo with flying saucer on force plate - same reading when it is resting on plate as when it is hovering above it.
Gave time for students to ask questions one on one.
Test tomorrow.
Andrew demonstrated jumping into the air.
Students predicted what a graph of normal force vs time would look like for his jump.
Discussed these graphs. Used force plate to observe the actual force vs time.
Talked about man on bathroom scale in elevator problems.
Suppose you have a jar of flies on an electronic balance and all the flies are sitting on the bottom. How would the scale reading change if the flies took off and flew around the jar. Referred to finger in water demo - the scale reading would not change.
Demo with flying saucer on force plate - same reading when it is resting on plate as when it is hovering above it.
Gave time for students to ask questions one on one.
Test tomorrow.
Thursday, April 17, 2008
Thursday, April 17, 2008
Collected problem 1 and then went over problems 2 and 4 on Applying Newton's Laws worksheet.
Handed out CD 5.2 and gave students time in class to do it.
Corrected CD 5.2. If students had mistakes, gave it back for them to correct and hand in again.
Assigned problems 42, 43, 44, 45 from the reverse side of the Applying Newton's Laws worksheet.
Handed out CD 5.2 and gave students time in class to do it.
Corrected CD 5.2. If students had mistakes, gave it back for them to correct and hand in again.
Assigned problems 42, 43, 44, 45 from the reverse side of the Applying Newton's Laws worksheet.
Wednesday, April 16, 2008
Wednesday, April 16, 2008
Stamped and then went over RA 4.5, particularly the kicking football problem.
Showed that it is not possible to apply a force of 200 N to a piece of paper held in front of you. We estimated the mass, time, distance and calculated the acceleration and force - much less than 1 N.
Handed back RA 4.4
Handed out Applications of Newton's Laws Worksheets. Worked problem 3 after giving students a chance to think about it.
Assigned problems 2,4 for tomorrow and will give extra credit for clearly written, correct solutions to problem 1.
Assigned WebAssign Hewitt Chapter 4 Part 2 - due Sunday 10:30 PM.
Last day to hand in CD 6.1 is Friday.
Test on Tuesday of next week.
Showed that it is not possible to apply a force of 200 N to a piece of paper held in front of you. We estimated the mass, time, distance and calculated the acceleration and force - much less than 1 N.
Handed back RA 4.4
Handed out Applications of Newton's Laws Worksheets. Worked problem 3 after giving students a chance to think about it.
Assigned problems 2,4 for tomorrow and will give extra credit for clearly written, correct solutions to problem 1.
Assigned WebAssign Hewitt Chapter 4 Part 2 - due Sunday 10:30 PM.
Last day to hand in CD 6.1 is Friday.
Test on Tuesday of next week.
Tuesday, April 15, 2008
Tuesday, April 15, 2008
Stamped homework, RA 4.4.
Went over worksheet as a review of yesterday's demos.
Showed clips from Independence Day video. Hollywood does not understand Newton's 3rd Law.
Students did Horse Sense worksheet in class. Voted on best pictures.
Handed out RA 4.5 for homework due tomorrow.
Went over worksheet as a review of yesterday's demos.
Showed clips from Independence Day video. Hollywood does not understand Newton's 3rd Law.
Students did Horse Sense worksheet in class. Voted on best pictures.
Handed out RA 4.5 for homework due tomorrow.
Monday, April 14, 2008
Monday, April 14, 2008
Newton's 3rd Law introductory lecture:
Inanimate objects can exert elastic forces: demo with rubber band, laser beam on wall.
No such thing as an isolated force - forces come in pairs (pears)
Newton's 3rd law recipe: A acts on B, B acts on B
Demo with finger in water.
Demo with force sensors. Chris can't pull harder on Jake than Jake pulls on Chris.
Newton's 3rd Law: If object A exerts a force on object B, then B exerts a force on A that is equal in magnitude and opposite in direction.
Tug-of-War: Janae and Chris. The one who wins the tug-of-war is the person who pushes harder against the ground.
Action/Reaction forces never cancel out because they do not act on the same object. Because they do not act on the same object, they never appear in the same free body diagram.
Examples of action reaction pairs. Contrast with forces that are equal in magnitude but opposite in direction but are NOT action reaction pairs.
Action and Reaction for Different Masses: If you drop a ball, why does the ball fall down and not the Earth fall up? Same magnitude force = m A = M a. Ball has much less mass so it has larger acceleration. Earth has huge mass, tiny acceleration.
Magic tube: tube exerts upward force on ball, ball exerts downward force on tube. We can measure this extra force using a force sensor and, if the ball is falling at terminal velocity, determine the weight of the ball.
Hand out RA 4.4 (summary of class notes) due tomorrow.
Hand out CD 6, due for the last time on Thursday.
Inanimate objects can exert elastic forces: demo with rubber band, laser beam on wall.
No such thing as an isolated force - forces come in pairs (pears)
Newton's 3rd law recipe: A acts on B, B acts on B
Demo with finger in water.
Demo with force sensors. Chris can't pull harder on Jake than Jake pulls on Chris.
Newton's 3rd Law: If object A exerts a force on object B, then B exerts a force on A that is equal in magnitude and opposite in direction.
Tug-of-War: Janae and Chris. The one who wins the tug-of-war is the person who pushes harder against the ground.
Action/Reaction forces never cancel out because they do not act on the same object. Because they do not act on the same object, they never appear in the same free body diagram.
Examples of action reaction pairs. Contrast with forces that are equal in magnitude but opposite in direction but are NOT action reaction pairs.
Action and Reaction for Different Masses: If you drop a ball, why does the ball fall down and not the Earth fall up? Same magnitude force = m A = M a. Ball has much less mass so it has larger acceleration. Earth has huge mass, tiny acceleration.
Magic tube: tube exerts upward force on ball, ball exerts downward force on tube. We can measure this extra force using a force sensor and, if the ball is falling at terminal velocity, determine the weight of the ball.
Hand out RA 4.4 (summary of class notes) due tomorrow.
Hand out CD 6, due for the last time on Thursday.
Thursday, April 10, 2008
Wednesday, April 9, 2008
Tuesday, April 8, 2008
Review for tomorrow's test.
I checked student answers and went over questions that gave difficulties.
Answered any other questions on other WebAssign problems.
Students worked on a review problem sheet and could check answers against a key.
Reviewed what to expect on tomorrow's test and things to pay particular attention to.
I checked student answers and went over questions that gave difficulties.
Answered any other questions on other WebAssign problems.
Students worked on a review problem sheet and could check answers against a key.
Reviewed what to expect on tomorrow's test and things to pay particular attention to.
Monday, April 7, 2008
Monday, April 7, 2008
Handed back Air Resistance Labs. Went over and answered questions.
Compared and contrasted contact friction and air resistance.
Answered questions from WebAssign.
Showed the rest of the Hewitt video with emphasis on why when you drop two different masses they will hit the ground at the same if air resistance is negligible and the idea of air resistance.
Handed out Problem Solving strategy sheet.
Handed out Newton's Laws Practice problems. Students worked on them in class. I supplied an answer key.
Compared and contrasted contact friction and air resistance.
Answered questions from WebAssign.
Showed the rest of the Hewitt video with emphasis on why when you drop two different masses they will hit the ground at the same if air resistance is negligible and the idea of air resistance.
Handed out Problem Solving strategy sheet.
Handed out Newton's Laws Practice problems. Students worked on them in class. I supplied an answer key.
Friday, April 4, 2008
Friday, April 4, 2008
Collected Air Resistance Labs.
Went over friction worksheet - did all problems.
Went over problem solving strategy for Newton's Laws.
Two Interesting Problems with Real Life Applications:
1. Showed that if you push up on an object, the normal force decreases and the friction force decreases. Useful for football linemen.
2. Pulling car out of the mud problem.
Started Hewitt video.
Two WebAssign Assignments. Hewitt one due Monday. Students should try second one.
Went over friction worksheet - did all problems.
Went over problem solving strategy for Newton's Laws.
Two Interesting Problems with Real Life Applications:
1. Showed that if you push up on an object, the normal force decreases and the friction force decreases. Useful for football linemen.
2. Pulling car out of the mud problem.
Started Hewitt video.
Two WebAssign Assignments. Hewitt one due Monday. Students should try second one.
Thursday, April 3, 2008
Thursday, April 3, 2008
Went over Newton's Worksheet. Included calculation of coefficients of friction in some of the problems.
Handed out worksheet on friction to give students more practice in using the coefficients of friction.
Worksheet is due tomorrow.
Test is next Tuesday. All Concept Dev sheets are due on Tuesday.
Handed out worksheet on friction to give students more practice in using the coefficients of friction.
Worksheet is due tomorrow.
Test is next Tuesday. All Concept Dev sheets are due on Tuesday.
Wednesday, April 2, 2008
Wednesday, April 2, 2008
Reviewed Friction Lab
Demonstrated static vs kinetic friction using bricks and force sensor.
Reviewed factors affecting contact friction: Normal force and surface texture
Discussed factors affecting air resistance: Speed and cross sectional area
Described Air Resistance Lab
For write-up: Answer preliminary questions 1-4, show data table with all raw data and averages and then square of average terminal velocity, 2 graphs (analysis question 1), Which model gives the best fit straight line through the origin?, Which model best describes air resistance for the falling coffee filter, analysis question 4.
Lab write-up due on Friday.
Students did the air resistance lab.
Demonstrated static vs kinetic friction using bricks and force sensor.
Reviewed factors affecting contact friction: Normal force and surface texture
Discussed factors affecting air resistance: Speed and cross sectional area
Described Air Resistance Lab
For write-up: Answer preliminary questions 1-4, show data table with all raw data and averages and then square of average terminal velocity, 2 graphs (analysis question 1), Which model gives the best fit straight line through the origin?, Which model best describes air resistance for the falling coffee filter, analysis question 4.
Lab write-up due on Friday.
Students did the air resistance lab.
Tuesday, April 1, 2008
Tuesday, April 1, 2008
Collected Newton's Packet.
Factors affecting friction - class lab.
Introduced coefficient of friction.
Factors affecting friction - class lab.
Introduced coefficient of friction.
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