AP Physics:Is Momentum Conserved in Osmos?

Learning Objectives

Students will design an experiment to determine if momentum is conserved in the video game Osmos.

Assessment Type
This activity can be used as a formative assessment, extracurricular project, or challenge problem for advanced students. There are multiple methods that could be used to answer the question. The ultimate goal is to promote student creative thinking and problem solving.

Assignment Details

• Students should begin by downloading and installing the free demo of Osmos, which is available on a variety of platforms including Windows and Mac computers (http://www.hemispheregames.com/osmos/). Osmos is also available for purchase through the iTunes App Store for iPad, iPhone, and iPod Touch.
• Students should experiment with the game to learn how it works. In particular, students should recognize how the conservation of momentum is essential to motion within the game. 
• Students are challenged to answer the following question: Is momentum conserved when the mote propels itself? 
• Students are asked to design an experiment to answer this question. In particular, they must clearly outline: 
• The process they followed to reach their conclusions.
• The data they collected
• The assumptions they had to make.
• The calculations they performed. 
• Students should submit their solution in the form of a 2-page report or a 2 minute video. 

Instructor's Notes

• In order to answer this question, students will have to wrestle with these additional questions:
• How does the mass of the player mote compare to the mass of the expelled mote?
• How can we determine the velocity of the motes?
• Do we need to know the absolute velocity or will relative velocity suffice?
• You may recommend that students use video analysis software to collected data on motion within the video game. By using a combination of screen capture software (such as Jing) and video analysis software (such as Tracker) students can extract numerical data to draw their conclusions.
• A few well-timed screenshots could also be used instead of video analysis to measure the recoil of each mote and ultimately answer the question. 
• The following could be used as a simple rubric for evaluating this student project:
• (10 pts) - Process for solving the problem is clearly outlined and accurate
  (5 pts) - Assumptions are appropriate and data is collected
  (5 pts) - Calculations are accurate and solution is correct.
  

AP Physics:Newton's Laws in Three Pictures

Learning Objectives

Students will be able to recognize Newton's Laws of Motion in ordinary situations.

Assessment Type
This activity can be used as a formative assessment to check student's conceptual understanding of Newton's Laws of Motion.

Assignment Details
Ask students to go around the school, looking for examples of Newton's Laws of Motion. When they find a situation that illustrates one of Newton's Laws, students should take a photograph using a digital camera (cell phones would work fine).

After returning to the classroom, students should write a brief description of how each image illustrates one of Newton's Laws. For example, a student description for the images above may look like:

1st Law: A stapler is sitting on a desk illustrating that objects at rest will stay at rest.

2nd Law: When pushing someone on a swing, a greater force must be applied to someone with a greater mass in order to achieve the same acceleration.

3rd Law: When the hamster runs in his wheel, there are two forces between his feet and the wheel -- one pushing his feet forward and the other pushing the wheel backward.

Instructor's Notes
Students can use one of several free online tools to create an animated .gif of their images (as above). The student's work can then be added to a class website, showing all the different ways Newton's Laws can be found in everyday life.

This same activity can be used to check student understanding for a wide variety of conceptual topics in AP Physics. For example, conservation of momentum, oscillations, refraction, and resonance would all make for an interesting series of photos.

As a formative assessment, this activity could be graded on a completion basis. Rewards, such as placing the best examples on the class website, could be used to motivate students toward excellent work.