In Class Activity Plan
Week Nine: Investigating Forces Part II
So it turns out that the plan from week 8 was a little more than a single week could hold, so we�re still doing some of that stuff.
20 min Practice with Force Diagrams (Word, Pdf)
PURPOSE: Practice making, using, and interpreting force diagrams in conjunction with system schema.
Notes:
o Have them draw two different system schema for each of the similar situations, particularly for the ball leaving the hand problem
o This is a reasonable worksheet to give as a homework as well
10 min Board Meeting
PURPOSE: Build consensus on the practice of making, using and interpreting force diagrams in conjunction with system schema.
Video Examples: (Discussion1, Discussion2)
o System schemas should have an arrow for every interaction
So the case where the ball is no longer in the hand, there is no interaction between the ball and hand and thus there can�t be any force
Watch for students trying to put 2 labels on a single arrow!
o System schema and Force Diagrams should be consistent with each other
Fnet is the direction of the acceleration
Directions are important
20 min Whiteboard � Scales in an Elevator (Word, Pdf)
PURPOSE: Gain experience reasoning conceptually with force diagrams.
Video Examples: (Boarding1, Boarding2, Boarding3)
Note: Probably want to whiteboard this, watch for same things as above. Emphasis on the direction of the acceleration matching the direction of the Fnet
20 min Board Meeting
PURPOSE: Gain experience reasoning conceptually with force diagrams.
Note: Probably want to whiteboard this, watch for same things as above. Emphasis on the direction of the acceleration matching the direction of the Fnet
15 min Whiteboard - Newton�s Second Law Variations on a Theme problem #1 (Word, Pdf)
PURPOSE: Practice modeling phenomena with new law, N2, and new representational tools.
Notes: They will try very hard to just answer the question without making a model
10 min Board Meeting
PURPOSE: Build consensus about modeling phenomena with new law, N2, and new representational tools.
15 min Whiteboard - Newton�s Second Law Variations on a Theme problems #2 & 3 (Word, Pdf)
PURPOSE: Practice modeling phenomena with new law, N2, and new representational tools.
Notes: Split up #2 & #3, have half of the class do one and the other half do the other.
Individual Problem notes:
o #1 - #3: All the same situation
Why bother? � Different quantities are given so we can find certain other quantities
It�s always the same system schema and force diagram
10 min Board Meeting
PURPOSE: Build consensus about modeling phenomena with new law, N2, and new representational tools.
Video Examples: (Discussion)
25 min Whiteboard - Newton�s Second Law Variations on a Theme problems #4 or 5 (Word, Pdf)
PURPOSE: Practice modeling phenomena with new law, N2, and new representational tools.
Notes: Split up #4 & #5, have half of the class do one and the other half do the other.
20 min Board Meeting
PURPOSE: Build consensus about modeling phenomena with new law, N2, and new representational tools.
Video Examples: (Discussion1, Discussion2)
Notes on each problem
#4 They don�t like the force from the rope on the child, and will try to put the force of the child on the rope in their force diagrams
#5: Using energy to get the velocities is a lot simpler. There are two parts to this problem (the way up and the way down)
Homework: Box on Box Problem (Word, Pdf)
Note: You will come back to this homework at the end of the upcoming lab. So it�s important that it is assigned before finishing the Newton�s 3rd Law Lab.
60 min Newton�s 3rd Law Lab: Investigating Forces Part Two (Word, Pdf)
PURPOSE: Introduce Newton�s third law to models
Technical Notes:
o Have the students open the file for Newton�s Third Law in Logger Pro
Logger Pro � Experiments � Physics with Vernier � 11 Newtons Third Law.cmbl
(This automatically has one of the force sensors with direction reversed so that you get positive values for one and negative for the other)
o Remember to calibrate the force sensors upon plugging them into the LabPro
Go to: Experiment � Calibrate � Calibrate Now �
� (1) Enter 0N into the box when nothing is on the hook of the force sensor � Press KEEP
� (2) Enter 9.8N into the box with a 1kg mass hanging from the force sensor � Press KEEP
o The force probes on the carts need to have the wide stoppers on them so that when they collide together, they actually push evenly on the stopper.
o The sampling rate should be increased to at least 500 samples/sec
Go to Experiment � Data Collection� �Sampling Rate
20 min Whiteboard
PURPOSE: Describe results of Newton�s 3rd Law Lab
Video Examples: (Boarding1, Boarding2)
o What did you learn?
o What rules can you make?
o What would you say to your friend about the SUV argument?
45 min Board Meeting
PURPOSE: Synthesize results of Newton�s 3rd Law Lab; introduce N3 to as law that models must obey.
Video Examples: (Discussion)
Goals:
o System schema for each different set-up
The force sensors measure the contact interaction in the schema
Each sensor reads one force, but it is the same interaction (2 forces for each interaction)
o Newton�s 3rd Law: �For each interaction, there are two forces one on each object, the forces are equal in magnitude and opposite in direction.�
o Rethink your box on box problem, carefully label each force, what is the same?
o Define Newton 3rd Law pairs as: the two forces that describe the same interaction
25 min Whiteboard - Identifying Newton�s 3rd Law Pairs (Word, Pdf)
PURPOSE: Integrate N3 into use of force diagram representational tool.
20 min Board Meeting
PURPOSE: Build consensus about integration of N3 into use of force diagram representational tool
60 min Whiteboard - Practice with doing Force Problems
PURPOSE: Build consensus about modeling phenomena with Newton�s laws, new representational tools, integrating force with other approaches to modeling phenomena.