Beginning of Radioactivity--Picture notes.

FINDING OUT ABOUT THE NUCLEUS

Thomsen's Experiment

Rutherford's Model

Chadwick and Millikan

Watch the full episode. See more NOVA.

RADIATION AND PROBABILITY

The Basics

The Dosages and Such

Friday, August 27, 2010

Modeling and Questions about Radioactivity

1. a) Using things available in the classroom, construct a model of the Rutherford experiment.

2.
   a) Explain the difference between a detector and a probe.

   b) Explain the difference in half life between two isotopes

   c) Contrast fission and fusion.

   d) How would you respond to an extremely obsessive person who wanted to avoid radiation at all costs.

Projectile motion model writeup

1. You built a catapult . Adjust it so that it is capable of launching a large marshmallow from a distance of 3 to 5 meters, and hitting a target that is .30 m high +/- .10 m. You will have 5 trials to hit your target at each distance on Friday, and will be graded according to your accuracy. (10 points)

2. Determine the variables for the y(down) and x for your catapult.  Base your calculation on d(y) and x(y), both which were measured.  SHOW WORK. (15 points)

3. Where is the biggest frictional issue in your machine? Explain why this matters to the range of your machine. (3 pts)

How could you determine F(net) of the projectile? (3 points)How will the net force of the projectile change if we use marshmallows instead of paper wads? An orange? Why?(3 points)
Explain how you would change the design if you built another machine, and what you have learned about projectiles. Include the following terms in your discussion about projectiles.: potential energy to kinetic energy changes, frictional force, net force, acceleration of gravity, vectors, kinematic equations, independent x and y motions. (15 points)

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Compare the physics engine used in your cartoon to the physics engine used in your game, using the data you captured in screen shots to support one of the following:

1.  Both the cartoon and the game have great physics.
2.  Neither the cartoon or the game have great physics.
3.  One of the two is obviously superior.

This should be close to a page when done
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Use your paperwad data and see how close your value of C in the quadratic analysis came to -5 m/s/s
In fact, you can calculate the percentage error by using (x-5)/5, since the acceleration of gravity is 10 m/s/s.

Why does your data match or not match this idea?

Explain, using your screen shot as evidence.

Understanding projectile motion models

This project is focused on seeing how projectile motion is used in digital media as well as common experience.  You must complete all projects, and put a screen shot of each data analysis in a shared Google folder.

Throughout this effort, you will need to use Vernier Logger Pro, the web cam, and/or http://www.screencast-o-matic.com/screen_recorder 

Part 1:   Take a video of your partner shooting a paper wad into the wastebasket.   You must be at a right angle to the person so you can see the entire arc of the parabola.  Analyze it using the Logger Pro.  Fill out the 15 variable chart, indicating on the screen shot where you started and ended the parabola.

Part 2:  Analyze the parabolic motion on a cartoon.  This is a great opportunity to use screencast-o-matic and a youtube video in conjunction with video analysis.  Again, fill out the fifteen variable chart.

Part 3:  Build a catapult capable of CONSISTENTLY hitting a sheet of typing paper from a distance of 3-5 meters.  You will calculate the range, v(i) in both directions, and maximum y-displacement.  You will be graded on the number of hits in 6 trials.

Part 4:  Analyze a video game physics engine to decide if the game is realistic or not.   The game must be approved by me in advance.

Part 5:  Go to http://phet.colorado.edu/en/simulation/projectile-motion and launch the applet.  Provide evidence (screenshots) to answer the following questions:

1.  How does air resistance change the path of a projectile?

2.  Shoot a single projectile at the same speed, but at 20, 30, 60, 70 , and 80.  Use this information in some way to determine the maximum range of a computer.

Guilty Until Proven Innocent

Problem:

How can you use the conservation of momentum to prove to a judge that you were not speeding and therefore do not deserve a ticket for the collision?

Materials:

Paper, Logger Pro, video, safercar.gov, protracter, ruler.

Procedure:

You leave the school teacher's parking lot and are traveling north when you are broadsided by a car traveling east. The collision occurs in a school zone with a speed limit of 20 mph.  The impact throws you into the band practice field.

Following the collision the police officer determines that both vehicles had a speed of 22 mph (9.8 m/s). The driver of the other car is an adult and claims that you were speeding and consequently should receive a ticket. You are to prove your innocence by using the conservation of momentum.

Research:

What type of a vehicle were you driving?  What type of a vehicle was the other driver riding in?  Look again at the safety and the mass of these vehicles at the NHSTA site (http://www.safercar.gov  ).  Use the same vehicle you looked up earlier this week.

Your vehicle_______________           Mass or weight____________

Their vehicle_______________           Mass or weight____________

Decide on the units for your momentum and record here ____________

Draw a diagram of the two cars just prior to impact. You were headed north, the other car was headed East. Choose a scale (e.g., 1 cm = kg m/s) or freehand draw a diagram of the vehicles before AND after the impact your calculation .  

There are two possible cases.  In Case 1, you were going 20 mph.  In Case 2, they were going 20 mph.  One things for sure.  After the collision, you were stuck together and both of you traveled at 22 mph.

Do one set of calculations for each Case.

STEP 2:  MODEL THIS COLLISION USING two balls of similar diameters but different masses.  Because the collision described above is inelastic, the balls must stick together and slide after impact.

Summing Up (each person does this individually,1/2 to 1 page, and hands it in paper clipped to the diagrams)

1. Qualitatively explain, using your diagrams, how you know that you were not going faster than the adult. Remember that a ticket means higher insurance rates and a large fine.

2. Do you think you were you speeding?

3. How would angles affect your logic?

4. What evidence of impulse or guilt would the police collect in this action?
5.  Based on the safety rating of the vehicles involved, what do you think the extent of the injuries would be?
6.  What role did impulse play in the safety factors present in your vehicle?   

Momentum Actvity

Activity 1  http://www.physicsclassroom.com/class/momentum/Lesson-1/Momentum-and-Impulse-Connection  (there are 7 problems, and you must do at least 4.  SHOW WORK)
Activity 2  http://www.physicsclassroom.com/class/momentum/Lesson-2/Momentum-Conservation-in-Explosions (Do all 5 problems.  SHOW WORK)


=======Second 45 minutes===========

Activity 3 should be downloaded to a computer and filled out.  http://phet.colorado.edu/files/activities/3777/Solar%20System%20PhET%20momentum%20conservation.docx   Do not kill a tree--simply write down the work to show your answers.



Hand in at the end of the hour.  Each person should hand a sheet in.

Pool Table work

Part 1

1.  Determine mu of your pool table surface.#

2.  Determine the elasticity of the bumper using p(b)=p(a)  using logger pro and the Video Capture option.#

3.  Make a drafting sketch of the pool table using autodesks, google sketchup, or a paper pencil model.  It must be to scale.#

4.  Practice making shots where the ball recoils at 90 degrees, where the ball recoils at 180 degrees,  > 90 degrees, and the ball recoils at < 90 degrees. #

Part 2:  

1.  Use a cell phone or flip camera to document your expertise in #4.  #

http://www.wikihow.com/Play-Pool-Like-a-Mathematician

http://billiards.colostate.edu/threads/position.html

http://iptv.pbslearningmedia.org/resource/rttt12.math.anglepool/the-angle-on-pool/

http://www.angelfire.com/ks3/poolmath/mathematics_of_pool.html

http://merganser.math.gvsu.edu/david/reed03/projects/fowler/poolcalc.html

http://billiards.colostate.edu/threads/position.html

Part 3:

1.   Hand in a scaled model of your pool table that includes top and side views.  This may be done using graph paper, sketch-up, or a CAD program, but the final product must be digitized.

2.  Create a Logger Pro artifact for the two collisions that includes the dot diagrams on the video and your calculations from Monday.  The first one will use only the x-axis.   The second one will use the cue-ball going off at a right angle.  Send me a screen shot of these two videos after analysis
3.  Hand in the analysis for the 1-d  collision of the ball, showing me a) the momentum before the collision, b)the momentum after the collision, c) the net time the two objects  were in contact, and d) calculations of the change in momentum and the impulse Force.  This is most easily done using paper and pencil and then taking a picture of the finished project.  (Hint:  use the mass of the cue ball and the cue stick, or the mass of both of the balls)
4. A picture of your group and your pool table must be included.

Part 4:
Evaluate a pool table that is not your own from a different table cluster.

Net forces activity

Part 1:  use the applet found at http://phet.colorado.edu/en/simulation/the-ramp

First, take a look at the page found here.   http://phet.colorado.edu/en/contributions/view/3143 It has lots of labs, some good, some bad, that help people to figure out the basics of mu, horizontal force net, and forces on a ramp.

Pick one of these labs and go through it. Do not pick the same lab as another group at your table. TEAMS ABOVE THREE WILL NOT BE ACCEPTED.   Turn it in today.

Part 2:  to be done individually, on paper, while sharing the computer applet.

DESIGN TEST:   Last Friday, we had a net force worksheet that we have not graded--yet.  You will need to use this applet to help design a student lab that is not boring and easier to understand regarding net force on a hill.  The lab should create understanding for mu on a hill, force body diagrams, and use net forces to answer the following question:   Does the mass of an object change the mu of an object moving with net force along the ramp?.   

State the purpose of your lab:

Give directions, as needed:

Collect evidence:

Tell me what is analyzed:

Part 2 is due on Friday.