Category Archives: Physics

Uniform Acceleration: Lab Practical

Today in Physics we did the lab practical for the uniform acceleration unit.

The goal of the lab is to catch a small sphere, that is accelerating down an incline, in the driver’s seat of one of my CV buggies.

They start out by finding the acceleration of the sphere down the ramp and then the velocity of the car. After they have done this, I assign arbitrary distances to each group and they had to figure out where to place their cart in order for them to be in the same place at the same time.

All groups succeeded, but one got done a good bit earlier than the rest. I then challenged them to perform the same experiment off of the lab table. What followed was awesome.

The math was quite easy for the group but every thing else gave them grief. In the end they caught the ball in the cart by adhering to all of the calculated values and it was great.

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MTM Day 1

This year I am experimenting with a new progression in my physics classes. We started out with the Data Analysis or Scientific Thinking unit of the Modeling material, which I heavily supplemented with the Patterns Approach to Physics material. This unit took us approximately two weeks (90 minute, A-B block schedule) to complete.

After that we moved on to the Constant Velocity Model, with our primary focus being on interpreting and creating several different representations to represent the motion of objects moving with constant velocity. Some modelers start with this unit instead of the Scientific Thinking unit, but I love teaching data analysis to my students and feel that it helps acquaint them with the level of math necessary for the course. This year the CVM unit took me 10 classes (a couple of those were lost to school assemblies) to complete.

The traditional modeling curriculum then finishes up classic 1D kinematics by launching into a unit on Uniform Acceleration. However, after looking into several resources (Matter and Interactions, Six Ideas that Shaped Physics, Andy Rundquist, etc) I decided to divert and instead discuss Momentum next with my students. I feel like several of the sticking points from the force units will be resolved by using momentum as a spring-board into the other topics in physics.

For each unit I have been doing my best to follow in the footsteps of Kelly O’Shea and Casey Rutherford by making packets of all most of the materials students will receive throughout the unit. This helps them keep everything in one place and gives them a great study packet. Here is my packet for the Momentum Transfer Model borrowed heavily, but greatly reorganized, from the Modeling materials and from Kelly’s packet. I am not entirely happy with the packet right now as I need to find some good Impulse problems to include, but other than that I am very satisfied.

To introduce students to momentum we did a lab that investigates the motion of bowling balls. Typically, this is the paradigm lab for the unit on balanced forces, which always seemed a little out-of-place to me. Using this lab as an introduction to Momentum felt much more natural. After we had shared our findings it lead into a quick demonstration using a hover puck and then to Newton’s 1st Law. I love the way this sequence has come together just in the first day.

Next time, we will use a PhEt simulation to walk-through the derivation of the momentum equation similar to how it is introduced in the Six Ideas that Shaped Physics.