# Sail Fans

I got the idea for this experiment while driving around town. We were driving across the Bridge of Lions in St. Augustine, and I pointed out a sailboat that had a large fan-like propeller sticking up behind the sail. The propeller is attached to a generator, using the wind to recharge the batteries. We joked about it being a fan to provide wind if the breeze died down, which lead to a discussion about what would happen if you tried that. That lead to this experiment.

To find out what would happen if you did mount a big fan to blow on the sails, you will need:

# Stirring Sand

I ran across the idea for this week's experiment (which is really more of a challenge), while researching another question. The more I thought about it, the more I liked it. It involves the unusual behavior of sand in a glass of water.

# Newton's Laws

This time we will investigate Newton's laws of motion. While Galileo laid the foundations for them, Newton was the one that put them into the form that we know them today.

# 944

If I roll the ball around the paper plate in the direction of the blue arrow, when it gets to the place where I cut out part of the plate, which path will it take? A, B or C? Why?

# 957

I photographed this snow structure on the drive home from the Utah Science Teachers Association conference. It is about six inches across, and there were many more of different sizes. How did it form?

# Sorting Salt and Pepper, How Many Ways?

In the Sorting Salt and Pepper video we saw that we could mix salt and pepper into a pile and then separate them easily by using the static charge on a balloon. That is one way to separate salt and pepper, but there are many others. How many can you think of? Don't read any more until you have spent some time thinking of as many different ways as you can.

# Stirring Sand, part 2

In part one, I left you with a challenge. We put a little sand into a glass of water and stirred it. Instead of moving to the outside edge, as we might expect, the sand gathered in the center of the glass. I left you with the challenge of telling me why.

Congratulations! Several of you got the right answer, and several more got it at least partially right.

# Measuring Kinetic and Potential Energy

I developed this activity while producing some science videos to go with a science textbook. They wanted students to be able to measure potential and kinetic energy, using everyday objects. Thanks to the abundance of cell phones, this is an easy way to do that.