collaborative labs

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Phy 121

Your 'collaborative labs' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.

** Collaborative Labs_labelMessages.txt **

10/31 4:22

I haven't been assigned a team for the first set of collaborative labs.

What do I need to do?

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I had some interesting groups set up, but some students are working at different paces, and some have dropped.

The last drop date is coming up in a couple of days. After that we'll address collaborative labs with groups of students who are committed to the course. We'll probably do only one collaborative lab, and I'll be asking for additional suggestions on the labs. There are already a number of good suggestion for the first collaborative lab, but now that everyone has done additional labs I want to give everyone a chance to express their ideas.

We have some excellent students in these courses and I think you'll enjoy working with your group.

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You have completed the first series of collaborative labs.

In that series you developed some important skills with teamwork, collaboration and communication. By now you have also developed additional lab techniques and insights, as well as an expanded understanding of physics and the standard formulations of motion, energy, momentum, forces and other topics.

You now have a good idea of the function of each member of the team, the designer, the experimenter, the analyzer and the interpreter.

You are also familiar with the items in your lab materials package.

The second series of activities will be spread out over the remainder of the semester. The investigations in this series will be more substantial and extensive than those of the first series, though we will limit the scope to keep the workload reasonable.

Please give a brief statement of three proposals for the second series of investigations.

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Two of my ideas involve momentum, the other involves horizantal velocity. The first momentum experiment will seek to provide evidence that when two masses of unequal mass but reasonably similar magnitudes of velocity collide, the object with the larger mass will have a greater influence on the direction of motion after the collision.

The second momentum experiment will seek to provide evidence that if two objects of unequal mass collide (in separate trials) with a stationary object, the more massive object will cause the stationary object to move at a higher velocity.

The third experiment will seek to provide additional evidence that horizontal displacement of a free falling object depends on the time the object is in free fall.

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Discuss your first idea. How do you think it might be tested? What sort of items do you think might be required? How do you think your idea might be tested?

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The first momentum experiment will seek to provide evidence that when two masses of unequal mass but reasonably similar magnitudes of velocity collide, the object with the larger mass will have a greater influence on the direction of motion after the collision. To test this we would set up the 30 cm shelf piece on a flat surface with the large metal ball on one end and the small metal ball on the other. After practice trials to make sure we get a collision very close to the center of the shelf, we time the start, the point of collision and the time when each ball rolls off the end of the shelf. With a half dozen good trials we should be able to calculate the final velocity at collision, and the final velocity at the end of the shelf. We can then determine the influence of the balls on each other.

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This is an excellent idea. There are some interesting confounding factors, which can lead to some interesting subsequent investigations.

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This experiement requires:

30cm shelf piece

large metal ball

small metal ball

Timer Program

Another person to assist with either timing or starting the balls in motion. This doesn't have to be a classmate - just a friend or family member.

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Discuss your second idea. How do you think it might be tested? What sort of items do you think might be required? How do you think your idea might be tested?

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The second momemtum experiment will seek to provide evidence that if two objects of unequal mass collide (in separate trials) with a stationary object, the more massive object will cause the stationary object to move at a higher velocity. To test this we will place the large marble in the center of the 30cm shelf rack. Then we use place the small steel ball on one end of the rack. We give the small steel ball a quick initial push, observe when it hits the marble and observe when the marble rolls off the far end of the shelf rack. Simultaneously using the Timer program we record the moment of the initial push, the moment of collision and the moment the marble rolls off the track. We will then be able to calculate the velocity of the small ball at collision and its average velocity and the velocity of the marble as it rolls off and its average velocity. We do this for 5 trials

We repeat this process with the large metal ball attempting to get velocities similar to the ones achieved by the small metal ball.

The hypothesis will be supported if for similar velocities, the larger ball resulted in a faster moving marble.

This experiement requires:

30cm shelf piece

large metal ball

small metal ball

large marble

Timer Program

Another person to assist with either timing or starting the balls in motion. This doesn't have to be a classmate - just a friend or family member.

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Discuss your third idea. How do you think it might be tested? What sort of items do you think might be required? How do you think your idea might be tested?

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The third idea is a variation on the acceleration of a ball down an incline lab. In that lab the incline was changed to achieve different horizontal displacements. In my proposed lab, we will see if we can get different horizontal displacements by varying the free fall distance while keeping the incline constant.

We will set up the incline like we did in the original acceleration of a ball down an incline lab but this time just use the 2 domino set up. We will again use the board with paper and the carbon paper as before but this time we will vary the height of the board. We will start with the board on the ground below the table and do five trials, marking them as before. We will also time how long it takes to drop from the end of the incline to the board. We will repeat this process again but raise the height of the board by placing 1 and then 2 books underneath.

We should be able to see a difference in the landing positions based on how far the ball was allowed to free fall.

This experiement requires:

30cm shelf piece

Dominoes

small metal ball

paper

carbon paper

books

Timer Program

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Your instructor is trying to gauge the typical time spent by students on these activities. Please answer the following question as accurately as you can, understanding that your answer will be used only for the stated purpose and has no bearing on your grades:

Approximately how long did it take you to complete this activity?

1 hour

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