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Day 68: Analyzing Spectra

emission_spec

Astronomy: (I tried taking pictures of spectra, but the low lighting didn’t produce good photos.)

Lab 18: Analyzing Spectra

  1. Continuous Spectrum
    Look at incandescent bulb w/ spectroscope.
    Draw what you see and describe in words.
    Why is this called a continuous spectrum?
  2. Absorption Spectrum
    Look at the pink sheet w/ spectroscope.
    Draw what you see and describe in words.
    Why is this called an absorption spectrum?
  3. Emission Spectrum
    Look at the gas tube w/ spectroscope.
    Draw what you see and describe in words.
    Why is this called an emission spectrum?
  4. Element Identification
    Look at gas tubes A, B, & C w/ spectroscope. Draw what you see.
    Use spectra provided (pictured above) to identify each gas.
  5. Solar Spectrum
    Go to http://v.gd/solarspectrum
    Use the spectra provided to determine which elements listed are in the solar spectrum.

The “pink sheet” that produces an absorption spectrum is the pink plastic from a “neon glow slate.” I got mine years ago, but it seems similar to this one that Dollar Tree is selling. It absorbs yellow light, so when looking at white light passing through it, you see a continuous spectrum with the yellow part missing.

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NGSS Science and Engineering Practices:
#4. Analyzing and interpreting data

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Day 64: Collision Video Analysis

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AP Physics C: Students used Logger Pro to do video analysis of 2 colliding dynamics carts. Each student in a lab group was responsible for analyzing a different video, then share out results and look for patterns.

The videos are here: Live Photo Physics Colliding Carts. We used videos #31, 32, 34, and 45.

Students are already familiar with collisions from physics last year. So this year, we are focusing on how the center of mass moves and how the carts move relative to the center of mass.

TASKS:

  1. Create a graph showing the position of each cart and the position of the center of mass over time. Find slopes.
  2. Create a second graph showing the position of each cart RELATIVE TO the center of mass over time. Find slopes.
  3. Determine the total momentum of the system before and after the collision.
  4. Determine the total kinetic energy of the system before and after the collision.
  5. Determine the fractional change in internal energy of the system as a result of the collision.

CONCLUSION:

Compare/contrast your results with the others in your group:

  1. Does the velocity of the center of mass remain constant always/sometimes/never?
  2. In the center of mass reference frame, what do you notice about before/after velocities of each cart for elastic and inelastic collisions?
  3. Is momentum conserved always/sometimes/never?
  4. Is kinetic energy conserved always/sometimes/never?

NGSS Science and Engineering Practices:
#4. Analyzing and interpreting data
#5. Using mathematics and computational thinking
#7. Engaging in argument from evidence

Day 62: False-Color Images

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Astronomy: Today we did a false-color image activity.

Devise a color palette for the picture:

  • You may use only 4 different colors.
  • Assign each color a brightness key.

falsecolorimageactivity

Look at each classmate’s picture and answer:

  1. What is different and what is the same as you look at everyone’s picture?
  2. Compare the pictures in terms of the pros and cons of using different color palettes.
  3. When you choose a different color palette, do the data change, or do we just see the data differently? Explain.

Here’s a copy of the student sheet: ASTRO Color Coding Activity
(Adapted from a Hands-On Universe activity.)

NGSS Science and Engineering Practices:
#2. Developing and using models
#4. Analyzing and interpreting data

Day 60: Another Single-Sentence Lab

exdck

AP Physics C: Yesterday I wrote about a single-sentence lab we did in College-Prep Physics. We also did a single-sentence lab in AP yesterday and today:

Determine the rotational inertia of a bowling ball using 2 different and independent methods.

NGSS Science and Engineering Practices:
#3. Planning and carrying out investigations
#4. Analyzing and interpreting data
#5. Using mathematics and computational thinking
#7. Engaging in argument from evidence

Day 59: A Single-Sentence Lab

College-Prep Physics: Today I tried an idea from Andrew Morrison (blog, Twitter), which appeared in the November issue of The Physics Teacher: Single Sentence Labs. Andrew writes, “a truly authentic scientific experiment does not come with any instructions.”

So as an introduction to our unit on acceleration, students were given this single-sentence lab: Does a spring rolling down an inclined lab table speed up? Justify your claim with evidence and reasoning.

It was fantastic. Lots of discussion within and between groups about possible experimental designs and analysis.

Some students went the traditional stopwatch and meter stick route:

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Others asked for motion detectors:

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One group did video analysis:

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On Friday, we’ll share our experiments and results.

NOTE: Last year, I did something similar, but used batteries instead of springs. Since the springs are hollow, they have a larger rotational inertia and accelerate more slowly than batteries. It takes about 5 seconds for the springs to travel the length of the 6 foot lab tables at a slight incline (about 3 volumes of Conceptual Physics texts high). I assume PVC pipe cut to pencil length would work well, too.

NGSS Science and Engineering Practices:
#3. Planning and carrying out investigations
#4. Analyzing and interpreting data
#5. Using mathematics and computational thinking
#7. Engaging in argument from evidence

##CAPM

Day 57: Balanced Force Lab Practical

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College-Prep Physics: Today we did a balanced force lab practical to tie together all our work on forces. It’s similar to the ones I’ve written about in past years. However, this year we used the green buggies and whiteboards instead of wood blocks and carpet/rubber. (This is because this year, in previous labs, some groups already worked with wood blocks and carpet/rubber.)

Given only a green buggy, a whiteboard, a spring, a 200-gram mass, and a ruler:

  1. Determine the spring constant of your spring.
  2. Determine the weight of your green buggy.
  3. Determine the force of kinetic friction between your buggy’s rubber tires and your whiteboard.
  4. Determine the coefficient of kinetic friction between your buggy’s rubber tires and your whiteboard.
  5. Predict the force of kinetic friction when 500 grams is added to your buggy. Have your teacher test your prediction!

UPDATE 2014 DEC 3: We found that when the 500 gram mass is added to buggy, the buggy rolls (rather than slide) when pulled. A binder clip on a rear wheel works great to lock the wheels so the buggy slides.

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NGSS Science and Engineering Practices:
#2. Developing and using models
#3. Planning and carrying out investigations
#4. Analyzing and interpreting data
#5. Using mathematics and computational thinking

##BFPM

Day 54: Kinetic Friction

College-Prep Physics: Last Thursday, students investigated the factors that might affect kinetic friction and how kinetic friction compares to static friction.

2015 CP 02 BFPM (1)

Today, students looked at the relationship between normal force and kinetic friction. Is the relationship proportional, like our previous experiments with static friction? If so, how do the slopes for kinetic friction compare to that from our static friction experiment?

2015 CP 02 BFPM (2)

NGSS Science and Engineering Practices:
#2. Developing and using models
#3. Planning and carrying out investigations
#4. Analyzing and interpreting data
#5. Using mathematics and computational thinking