Day 151: Rocket Engine Test

Wednesday, 13 April 2016

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If you’re gonna build rockets, you need an appropriate soundtrack.

Lesson plan:

  1. show video of a Saturn V launch
  2. show video of a model rocket launch
  3. what do you know about rockets? we have a lot to learn about physics concepts including momentum, impulse, and conservation of energy from model rocketry
  4. build Estes Viking model rockets (need: super glue, sand paper, and rocket kits). this and the above can be done in a 70 minute period.
  5. time permitting, test fire and collect force vs time graph data (need: force probe, rocket test stand)

 

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It helps to have old rockets available for the kids to see what they’re working toward.

Day 149: Hit Me with Your Best Shot

Monday, 11 April 2016

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We started this lab last week but once I saw the stress level of the kids as we headed into a unit test, I opted to move the lab to the first day after the test. The drawback, of course, is that the lab felt disconnected from our learning. The upside is that the lab went super-smooth.

Today, we verified our setups by checking a few data points from last week, then fired away. Almost everyone landed in the 2nd zone below my face (where the bowtie is) and a few landed right on my face.

This is one of those labs I call satisfying because it’s performance based and most folks do pretty well on it.

A few tweaks this year made this lab go better than ever before:

  • Make the zones into horizontal stripes rather than a bullseye. Removes almost all side-to-side problems.
  • Make the kids “buy” a second shot at the target, which is only useful if you completely miss the page on your first shot.
  • Require a 5 minute time limit between taping the target to the floor and the kids telling you where they’re dropping from.
  • Make ramp stands out of scrap wood for easier propping.

One tweak I want to do next year to get a smoother transition to the table:

  • 3D print a little triangle piece that snaps into the end of the ramp

Here’s one team’s first attempt at the target:

Here you go: Hit Me with Your Best Shot (Word file)

Day 146: Projectiles

Wednesday, 6 April 2016

Topic: projectiles launched horizontally

Here’s what it looks like when I set up a projectile problem. I like the way I can emphasize time being the one quantity that connects the two simultaneous motions.

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By the way, I define projectile motion as “objects moving horizontally and vertically simultaneously through the air”. Marbles rolled off a lab table are projectiles but airplanes are not (because lift, several kids told me). What about that baseball we threw in the air two weeks ago? Yep but fun fact, kids: the horizontal velocity is just zero.

Dudes, when I walked by this desk, I was blown away by the color coordination going on in this kid’s notes:

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How do I feel that this is a nearly exact copy of my version on the board? Yeah, yeah, I know it means she might not be processing the information. But I like the meaningful use of color too much to get worked up that the kid’s copying me verbatim. I think she’s processing something because fun fact: when doing examples, I stop at the givens (in green) and make the kids do all my algebra for me. So the purple work is entirely her own.

Day 144: Hit Me with Your Best Shot!

Monday, 4 April 2016

This is one of my top 3 favorite labs of the year — launch a projectile to (confidently) hit a target.

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Target page from the lab.

Above, a lab group collects data on the relationship between drop location on the ramp and horizontal velocity coming off the ramp. My students have already studied forces but I didn’t do anything with inclined planes, so yeah, there’s that caveat about the lab. It means that when one group graphed their drop location vs horizontal velocity data, the parabola was a bit of a pleasant surprise.

A colleague of mine hates the hop marbles take as they exit the ramp and enter the table. Yeah, it’s an issue. Maybe I could 3D print some triangles that’d fix most of the problem. The colleague uses flexible wood moulding to solve the transition problem.

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My colleague uses this stuff or a PVC version like it.

What I love about this lab is that it’s focused on a goal that’s easily understood without the physics — do a thing to hit a target. The Mirror Maze is my other favorite example. Both are low floor, high ceiling work, y’know?

Hit Me with Your Best Shot lab (PDF)

History: Here’s the 2014 version of this lab (note: I’m not running behind — we didn’t have a JanTerm that year.)