Day -2: My set-up for vertical non-permanent surfaces

image

Ended up using 2 ring stands with T bases to support the boards in front of the windows.
image

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.

119967

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

Day 67: Marshmallow Puff Tube

 

feel7

College-Prep Physics: We did an exploratory activity as an introduction to impulse. Another single-sentence lab:

LAB 13 — Marshmallow Puff Tube
Design several mini-experiments to determine the factors that affect the speed of the marshmallow.

Here’s the results from one group.

wpid-wp-1418685567795.jpeg

Sadly, no one thought to change the mass of the marshmallow:

wpid-img_20141215_092828448.jpg

More info about building marshmallow puff tubes:
http://www.exploratorium.edu/snacks/marshmallow_puff/

NGSS Science and Engineering Practices:
#3. Planning and carrying out investigations

Day 66: Collisions in the Center of Mass Frame

2015 APC Collisions

AP Physics C: Based on the results of our video analysis of collisions, we know that both momentum and kinetic energy are conserved in elastic collisions. So I as warm-up, students worked on the above problem on whiteboards.

After some flexing of algebra muscles and a messy simultaneous equation, I ask if they’d like to see a short cut….

Based on the video analysis yesterday, we also saw that the velocity of the center of mass (yellow) remains constant.

wpid-wp-1418422140765.png

And for elastic collisions, the carts pre- and post-collisions velocities relative to the center of mass were equal and opposite.

wpid-wp-1418421907597.png

So we applied those concepts to the above problem to generate an easier solution:

wpid-skitch.png

  1. Find the velocity of the center of mass.
  2. Find the initial velocities of the blocks in the center of mass frame.
  3. The final velocities of the blocks in the center of mass frame are equal and opposite to the velocities in #2.
  4. Translate the velocities in #3 back into their actual velocities.

NGSS Science and Engineering Practices:
#5. Using mathematics and computational thinking

Follow

Get every new post delivered to your Inbox.

Join 152 other followers