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December Meeting

posted Jan 26, 2010, 2:35 AM by Steve Dickie

DMAPT Meeting – December 2, 2009, Oakland Christian School

Host: Bryan Crump

DMAPT members met at Oakland Christian School on Wednesday, December 2nd.  Bryan Crump was our host.  The meeting focused on labs and demos related to momentum/collisions. 

Member announcements:

·      Don Pata noted that the workshop on using inquiry in the classroom and generating productive class discussion presented by Nicole Murawski and Laura Ritter on December 1st was awesome!   Don recommended that all attend future workshops.

·      Jeff Conn gave an update on the planned Astronomy BA program at Wayne State and provided information brochures.  The program will offer research experience for undergraduates and will be the only one of its kind offered in Michigan.  Interest in the program has been very strong.  Students with a BA in Astronomy would likely pursue careers with NASA, or enter graduate astrophysics studies.   Per Jeff, the recently initiated Biomedical Physics program at Wayne State is also going very well and is quite popular with students.

·       Jeff Conn also reported that a new digital planetarium is coming to Wayne State. 

·      Jeff informed the DMAPT members that the people who were interested in participating in the Supernova Search project will be getting an email from Dave Cinabro detailing the next steps in the project.  The program is waiting funding.

·      Al Gibson reported that the Galileoscopes have been ordered.   It was agreed that these would be incorporated into our April meeting.

·      Jeff Conn noted that Saturday, December 6th, 2009, is Noel Night in downtown Detroit.  This is an annual family-oriented event showcasing several institutions.  Wayne State does a planetarium show.  All venues are free of charge. 

Upcoming calendar events:

·      Nicole Murawski and Steve Dickie will be presenting an all day workshop on video analysis.  Date and location have not been finalized, but it will be on a Saturday in the spring at either the Wayne County RESA or at Royal Oak High School.

·      Al Gibson and Laura Ritter are presenting “Quantum Physics and Dark Matter” at the MSTA conference.  They are also presenting a unit on two dimensional motion and circular motion.  Both presentations will be on Saturday, March 6, 2010.

·      The DMAPT make-and-take session (with the Galileoscopes) at the MSTA meeting is scheduled for Friday morning, March 5, 2010.  Volunteers are needed to help with the session. 

Member sharing:

·      Don Pata shared a demo that he uses for collisions.  He starts by telling his students that they are in a car and a collision with a tree is inevitable.  He asks them whether they prefer to bounce off the tree or stick to it.  Most students will choose to bounce off the tree.  Don then uses “happy and sad balls” (http://www.arborsci.com/SearchResult.aspx?KeyWords=happy%20sad%20balls) to simulate the bouncing and sticking collisions.  Don hangs each of the balls from strings attached to a ring stand.  He stands a section of a 2 x 4 (approximately 1 foot long) vertically just in front of the balls.  Don then pulls each ball back and releases it so it collides with the 2 x 4.

·      Don follows up by asking the students to explain why the bouncing collision is worse, knowing what they know about momentum.  He has the students estimate the velocity of the ball before the collision and calculate the Dv.  Don then brings them back to the car collision scenario to reconsider their original answer.

·      Don next displayed a fan cart with a plate “sail” on it and asked what will happen when the fan is switched on.   Don noted that the Pasco pamphlet explains that the air from the fan hits the sail and bounced off, creating a Dv and increased force.  Is this a good momentum demonstration like Pasco suggests?

Taken from the Pasco website (ftp://ftp.pasco.com/Support/Documents/English/ME/ME-9485/012-05307E.pdf) :  There is a force on the cart in one direction resulting from the fan pushing the air and there is another force on the cart in the opposite direction resulting from the air hitting the sail. See Figure 2. But when the air hits the sail, the air bounces off the sail, causing more force on the sail than the force of the air on the fan. Therefore, there is a net force on the cart that causes the cart to accelerate.”

·      Chris Deyo shared a lab that she uses to have students determine the coefficient of friction.  A variation of the lab would be to have the students collect data and then create a system that provides an acceleration of ____.  She uses old wooden collision carts for the lab.  The lab can be found on her website.   http://www.rochester.k12.mi.us/index.aspx?folder=23390

·      Chris also shared a practicum on unbalanced forces.  The students are given a protractor, scale and the coefficient of friction and must predict the time for the system to move one meter.  This lab is also available on Chris’s website above.

·      Stephanie Spencer shared a simple lab that combines friction, work & energy and momentum.  The students are given a box, a tennis ball, a spring scale, a meter stick and a balance.  The box has one end open and a strip of Velcro attached to the inside of the box opposite the open end.  She used fruit snack boxes that are about 5” x 7” x 12”.  The students are challenged to determine the coefficient of kinetic friction, the velocity at which the ball & box combination move and the initial velocity of the tennis ball.

·      Bryan Crump demonstrated how he has students experience torque, using a bicycle wheel and a platform.   He also uses the bicycle wheel to discuss motorcycle turns.  This led to a discussion on precession.  Don Pata will put a precession explanation on the DMAPT website.

·      Mark Davids shared how he introduces momentum to students.  He begins by asking students what they have heard on momentum.   Typically, examples from sports are mentioned.  He then tosses a golf ball to a student and has them toss it back.  He then does the same thing with a baseball.  Next, he asks the students if the balls had the same projectile path, would they expect them to have the same momentum.  He generates a list of what the students think momentum depends on, such as size, mass, weight.   He uses a nerf ball and a baseball of equal size to eliminate that option.  If velocity wasn’t mentioned for the list, he tosses a ball at different speeds so that kids pick up on velocity as important to momentum.  Now that the list is narrowed to mass and velocity, Mark proposes that they could be combined by adding, subtracting, multiplying or dividing and leads discussion to arrive at multiplying.  He then has the class estimate the mass of golf ball (perhaps 40 grams) and a factor for the mass of baseball compared to mass of golf ball (perhaps 4 times).  He asks if the baseball and golf ball have the same velocity, could they the same momentum (only if zero velocity).

·      Mark continued with his “Off the Wall” lab.  The students are asked to consider a ball that is tossed, bounces off the wall, and is finally caught.  They are to identify three horizontal forces acting on the ball.   Next they are asked to explain how each force changes the sideways momentum of the ball.   Finally, they complete a table to rank change in velocity, change in momentum, Dt and force) for the throw, wall, and catch events of the toss.

·      For Mark’s final demo, he balanced a track on block. Two carts were set on the track above the balance point.  A loaded spring from the 0.5 kg cart is then sprung to push against the 1.0 kg cart.  Students are asked to predict what cart will move.  They are also asked to predict which end of the ramp will tip downward as the 1.0 kg cart moves to the right.  Finally, they are given force and Dt data and complete calculations for momentum and velocity for both carts 

Next meetings:

·      Our next meeting is tentatively planned for early February, 2010.

Steve Dickie,
Jan 26, 2010, 2:42 AM