Thursday, March 29, 2018

Simple Rack-and-Pinion gears (Mechanisms) - Page 115, Build #155

This is what we're building today - Rack-and-pinion gears.



Rack-and-pinion gears are used to change rotational movement (the yellow and gray gears with the rubber band going around it) to linear movement (the side-to-side movement going across the white pieces or racks). The steering system in cars is a good example of rack-and-pinion gears at work.

Parts I'm using today:

I'm making do with what I have. I'm pretty sure they'll work fine. If not, we'll just have to figure things out as we go.

Let's build:










1st design for the motor support.




In this state, it wasn't the white rack that moved from side-to-side, but the gears moving awkwardly.


So, I removed some support pieces, and stuck the motor on a bigger, anchoring piece. But this still moved things enough that the video didn't turn out very well. So, when I was recording the video, the gray platform had to be held down.

It was still neat to watch.





Here's a video. Enjoy!


Have a great day!

Wednesday, March 28, 2018

Awesome Reads - National Geographic, Black and White

I was coming back from Seattle this weekend, and I wanted something new to read. When I walked into a bookstore at the airport, this one really caught my eye.



Aside from many interesting articles, I was really struck by the fold-out below. We see things in terms of black and white (and I don't know why), but there are so many beautiful shades to us. The background color was picked based on the nose of the subject, and our palette is so broad and encompassing....  This picture stayed with me for a long time.


I'm going to ask my son and daughter to read this magazine, and I hope to have a conversation about the magazine.


Tuesday, March 27, 2018

Adventures in Biomedical Engineering - Heart Valve

This is a project I came across a while back, but I didn't have a chance to do it with a class. And I'm not sure if I will this year before summer vacation. So, I'm just going to do it.

I can't remember the details about this project, but if you're interested, you can look it up on either Science Buddies website or Teach Engineering website

We're going to be biomedical engineers today, and we're going to find ways to design and install a new heart valve, which will pump blood into the heart.


There are four heart valves in our hearts. Two valves pump blood into our hearts (Tricuspid valve - right side and Mitral valve - left side). 

These valves sit between atrium and ventricle. Two valves pump blood out of our hearts (Pulmonary valve - right side and Aortic valve - left side). 

The pulmonary valve (on the right side) pump blood into our lungs and the aortic valve (on the left side) pump blood to the rest of our body.

List of Supplies:

 
I just grabbed what I had. I didn't have any idea what I was going to do with these.
You don't need a plastic container. You can use a cardboard shoe box if you have one handy.


Different types of paper. I have a cardstock and a copy paper. I decided to use cardstock because it's stronger and the weight of the marbles won't affect it as much.


OK. Let's build!

The cardboard pieces are the blood vessel openings. 
We have to build something between the cardboards to let the blood (marbles) flow one way, but not back.

​Since I had popsicle sticks, I thought I'd use one of these to stop the marbles from rolling back to the original side (atrium side).

This design took more than four tries to get all the marbles across the other side, and the marbles got stuck under the slide.

This design took four tries to get all the marbles across the other side, but the marbles didn't get stuck.


Even though I rocked the container back and forth to get the marbles across, none of the marbles escaped back to the right side. So, the "valve" functioned as it should. But now, the challenge is to do it in less tries. To make a more efficient "valve."

I really like this project, and I'm going to try to do this with my class before the school year is over. I hope you get a chance to try this one, too.





Wednesday, March 21, 2018

Whirly Birds - A study in Hydrodynamics and Biomimetics

I know. It's a mouthful, isn't it? But this is a great project.
I've been doing it for a long time, and every time, the students love it, whether they are in 2nd grade or 6th grade.
This is what we're making today.


An important disclaimer first. I got this project idea from science buddies.
Please check out www.sciencebuddies.com. It's a great place for project ideas.
Before I start the project, I discussed the concept of biomimicry. Simply, it means that engineers are trying to use what we find in nature to improve functions of man-made objects. A splendid example is velcro. It was invented by a man who went for a walk with his dog and came home with a lot of hooked burs from the local hills on his socks and his dog. He studied the burs and invented velcro. Imagine that!
Cat's Paws and Catapults by Steven Vogel has a book full of Biomimetics examples. You might want to check it out.
So, what is biomimetics?
Studying and Learning from Nature
One of the best examples of Biomimetics is velcro. A Swiss engineer took his dog for a walk and found these things clinging to his dog's belly and legs. It took a long time for him to take these things off, and one day, he looked closely at the things he was taking off his dog. He found these tiny hooks at the end of the things that were clinging to the stomach and eventually invented velcro. Can you believe it?
Sciencebuddies.org used to have a wonderful lesson associated with this, but it's no longer available (at least I couldn't find it). So, I'll have to do my best to give you a short summary.
The bumps on humpback whales' fins called tubercles (scalloped pattern)
help the whales swim through the water easily.
The spikes on sharks' skin called denticles (saw-tooth pattern)
help the sharks slice through the water effortlessly.
Scientists and engineers are working to incorporate these design elements to planes and ships, among other things. They believe that if we could put a thin skin of these patterns on our planes, it might cut our travel time over 50%!
Imagine that!
For this project, you need to cut out the three separate patterns, test them and figure out which pattern helps the whirly-bird slice through the air best.
When I do this project in class, I'm the client and the students are aerospace engineers who are competing in teams to win a chance to build a revolutionary new aircraft. They must test the three patterns and make recommendations according to their flight data (how long the various whirly-birds took to reach the ground).
List of Supplies:
  • Paper, to copy the whirly bird designs on them.
I've used different kinds of paper in class (plain copy paper, construction paper and cardstock paper), and it really doesn't matter what kind of paper, as long as they are different. I want the students to notice the difference in flight.
  • Scissors
  • Craft scissors for make patterns.
It would be nice to have scalloped and saw-tooth patterns, but this is not a must have. Any sharp vs. curvy pattern would do.
  • Pencil and notebook paper to take down data.
I have the students count in their own consistent way to keep track of how long it takes for the whirly-birds to reach ground.
Build instructions:
  • Cut along the outside solid lines.
  • Cut the side lines (about midway down) and the blade lines.



If you have craft scissors, use them to make the cuts. If you don't have the craft scissors, make the cuts like the patterns, but you don’t have to follow the pattern exactly. As long as you get a saw-tooth pattern (sharp and pointy) and a scallop pattern (rounded and wavy), they should work.
  • Fold length-wise, along the bottom half of the whirly-birds




  • Fold the sides in.
  • Fold the blades out in opposite direction.



  • Hold it out in arm's length and release gently.



Don't try to throw it. The best results come from gently letting it go in the air.
And how fast it reaches the ground is important, but what's more important is how smoothly the blades slice through the air as it descends to the ground.
Basic Design
After students have tested the three basic designs, I ask them to make designs of their own. There are no restrictions here except that the students CANNOT leave their whirly-birds in their original design.



I was hoping to attach a link to this pattern from sciencebudies.org, but this pattern is no longer available, but the patterns look like this.



Again, rounded, scalloped pattern represents the whale tubercles, and the saw-tooth pattern represents the shark denticles. The straight line represents the standard blade-edge design for helicopters, wind turbines, etc.


When I do this project in a classroom, kids line up 3 to 4 in the front of the classroom. Then they release their best whirly-birds at the same time, and the teacher and I judge according to the smoothness of the flight and how fast it descends to the ground.
Please note that the fastest whirly-bird isn't always the winner. We look at the smoothness and the beauty of the flight more.
Other things to look for in judging Whirly-Bird Olympics:
  • Flight patterns
  • Swirls
  • Turn speed
  • Creative Blade design
Have fun!