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.
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