# Hanging a Hammer

This experiment involves balancing a hammer, a ruler, and some string. It is one of those balancing tricks that seem as though they just should not work, even though you understand the science behind them. I first learned it when I was eight years old, but it is still one of my favorites.

# Is Gravity a Theory or a Law?

I frequently get emails wanting to know whether gravity is a law or a theory. That question brings up so many more questions that I thought it would be fun to explore.

To try this, you will need:

- an object to drop.

# More Fish in a Bucket

Last time I left you with a question. We were imagining fish swimming in a container of water. When I was a child, I was told that you could put the container on a scale, and as long as the fish did not touch the sides or bottom; you would only be weighing the water.

We substituted a brick for the fish, and found that if we lowered it into the water, the scale went up enough to equal the weight of the water it displaced. Then we placed it on the bottom, and found that the scale went up to equal the full weight of the brick.

# Fish in a Bucket

This week's experiment goes back to fishing trips from my childhood. As we caught fish, we put them into a large tub of water. I loved watching them swim around and around. I was told that if you weighed the tub, that it would not register the weight of the fish, unless they touched the sides or bottom of the tub. Was that right? Let's find out.

# Floating Bubbles

This time we are going to produce some floating bubbles. Instead of filling the bubbles with hydrogen or helium, our bubbles will be filled with ordinary air, and will be floating on a layer of a heavier gas.

# 919

I weighed this bowl of water. If I stick my hand in the water, and weigh it again, will it weigh more? If so, how much more. If not, why not?

# 945

I weighed this plastic, storage bag while it was empty. Then I opened it to fill it with air. Sealing the bag again, I put it back on the scale. Was its weight the same, more, or less? Why?

# 946

A plastic, storage bag would not weigh more when it when it was filled with air, but when I blew up this balloon, its weight did increase. 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?