Complex Machines and Rube Goldberg

At the end of this Simple Machines section of our Robotics Unit, we had a fun day learning about Rube Goldberg Machines and making our own! It was hard work, but the children were SO proud of themselves when they actually got one to work!

After talking about some of the ways simple machines can be put together, we read some of Rube Goldberg's actual cartoons from this book. Some of them are really hilarious. The children liked me reading the descriptions and pointing to each part.

There are tons of awesome and funny Rube Goldberg machines online. Some of our favorite videos (some less on-point than others):

A funny Honda Commercial

"Dog Goldberg" machine

This machine made by high school students is pretty fun

This is sort of silly, but it has Rube Goldberg himself in it

The children LOVED this one by OK Go

And this one was our absolute favorite!! We watched it over and over.

We also watched this strange and mesmerizing movie (no words, just the machine working until it finally fades out. There's no grand ending, but the children still wanted to watch it multiple times.)

There were complicated and messy contraptions all over the house for several days after this.

We decided to try to make a toothpaste-squeezing machine like the one the children made in this post. I left it totally in the boys' hands (Daisy and Junie were napping) and it took them most of the day with lots of frustration and failed attempts—but they finally made it work! They were so happy! 

And, just for fun, here is Seb with his homemade "jet engine"

Electromagnets and Motors

It's pretty easy to make a simple motor. We got excellent instructions here. As you can see, it's just made of a battery, two safety pins (which act like wires to conduct electricity from the battery to the magnet wire, but serve the added purpose of having holes for the wire to spin through!), a coil of magnet wire, and a magnet. We used clay to hold the battery in place.

I would add, to the instructions linked above, that you should make your coil of wire by wrapping it around a size _C_ battery (not D)---otherwise it will be too large in diameter to turn freely. 

You also need to make sure to only scrape off the wire coating on half of the wire's diameter. In other words, the copper wire that goes through the safety pins will only be in contact with electricity for half the time--as it spins, the coating and the wire itself will take turns contacting the safety pins. This is essentially your commutator, allowing the direct current of the battery to alternate its path into the coil and thus keep the motor spinning.

Once you get it going, it should spin on its own for quite a while, and you can stop or slow it by bringing magnets close to the coil. It's really fun to play with.

We also made an electromagnet that could pick up paper clips when the current was flowing, but not when the circuit was broken.

More motor and generator stuff:

This page on motors, with animations, is really great

I think I linked this elsewhere, but we liked this information on AC vs DC motors

And this is a good video on the induction motor.

This generator project looked pretty fun. (Here is our previous, ill-fated attempt at a hydropowered generator--maybe taking out the hydropower component would make things simpler and less liked to go wrong!)

Here are Abe's and Seb's diagrams of how motors/generators work:

And the one we made all together