This is Members Only content.

Become a Member Today at the Introductory Price of
Only $20 for an Entire Year, and get full access to this site.

Can an empty space have only one side?

This is Members Only content.

Become a Member Today at the Introductory Price of
Only $20 for an Entire Year, and get full access to this site.

Big Numbers

How to grasp really big numbers.

This is Members Only content.

Become a Member Today at the Introductory Price of
Only $20 for an Entire Year, and get full access to this site.

What's the Password?

How easy is it to crack a password?

This is Members Only content.

Become a Member Today at the Introductory Price of
Only $20 for an Entire Year, and get full access to this site.

Measuring Lightning

How far away did that lightning strike?

This is Members Only content.

Become a Member Today at the Introductory Price of
Only $20 for an Entire Year, and get full access to this site.

Planets and Pennies

Want to see how much something would weigh on a different planet?

This is Members Only content.

Become a Member Today at the Introductory Price of
Only $20 for an Entire Year, and get full access to this site.

Can you really change the speed of light? Of course you can!

Last week, 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.

Now, for the question I left you with. What if you put the brick on a scale, and then submerged both of them in the bucket of water? How much weight would the scale show for the brick?

Hopefully, you spent some time thinking about it. We know that the brick felt lighter when we held it under water, because the water was pushing up on it with a force equal to the weight of the water it displaced. That gives us our clue. If the scale was in the water, with the brick on it, it would show the weight of the brick, minus the weight of the water it displaces.

We can find that, without even putting the scale in the water. If we take the weight of the brick and subtract the reading on the scale when we held the brick under water, we get the weight minus the weight of the displaced water.

But that still leaves one more thing to check, as a couple of clever readers pointed out to me. What if the brick (or fish) were suspended in the water without your hand or anything else holding it up?

Well that would be easy to test if we had a fish, but the closest thing I have is a can of tuna, and somehow I don't think that would work the same way. Instead, lets use a water balloon. After all, a fish, like most living things, is mostly water. If we fill a balloon with water, and put in a tiny bit of air, it should float just at the surface and make a very suitable fish replica.

OK, so what do you think will happen? Think about it another way. What if we left out the balloon, and just added the water? Would the scale show an increase of weight then? Yes, of course it would. Do you think that putting the water inside a balloon would change that? No. What about putting that water inside a fish? No, it would still show up as an increase in weight, and since the water is supporting the full weight of the fish, the scale would show an increase of the full weight of the fish, or in this case, the water balloon.

When I was younger, this experiment would have ended with me throwing the water balloon at my brother or my sister. Now that I am older, I wouldn't do that. They live too far away. Luckily, I am going home to see them this coming week, so I may take advantage of the opportunity to complete the experiment there.

Have a wonder-filled week.

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.

You will need:

- a bathroom scale
- a bucket of water
- a brick or large rock

Start by putting the bucket of water onto the scales, and recording the weight. Then pick up the brick and hold it under the surface of the water. Don't let it touch the side of the bucket. Look at the scale again. Has the weight changed?

Yes, the weight goes up. So the first part of what I was told was wrong. The tub of water did weigh more with the fish in it, even if they were not touching the tub. Well that certainly makes sense.

Next, touch the brick to the side of the bucket. Did it change? No. Touching the side of the bucket does not cause the weight to change. Again that makes perfect sense. Contact between the brick and the bucket (or the fish and the tub) does not make any difference. OK that makes perfect sense too.

Now, what if you placed the brick on the bottom of the bucket? Would the weight change then?

Don't try it yet. Instead, think about it for a minute. (Hint: Think about why some things float and some things sink.)

Alright, now try it. No, I did not say read what will happen. I said try it.

Did you try it? Good, then I don't have to tell you what happened, right? But, I will anyway. When you placed the brick on the bottom of the bucket and released it, the weight increased. Why?

When you put the brick into the water, you should have noticed that it seemed to weigh less in your hand. That is because the water was supporting part of its weight. The weight that you felt decreased by exactly the weight of the water that the brick displaced. The weight of the bucket increased by the same amount. That was the first weight gain for the bucket.

When you put the brick on the bottom of the bucket, your hand was no longer supporting part of its weight, so the weight of the bucket increased enough to register the full weight of the brick. That was the second weight gain.

Just one more question. What if you put the brick on a scale, and then submerged both of them in the bucket of water? How much weight would the scale show for the brick? You've got a week to think about it, or try it yourself.

Have a wonder-filled week.

For that, you will need:

- a container like a drinking glass with straight sides
- a ruler

Be sure that the container has sides that go straight up and down, with no slope. You want the bottom to be the same diameter as the top. I used a glass container for candles, and it worked very well. Place your container where rain can hit it. Do not put it near trees, buildings, or anything that would block some of the rain.

After a storm, use the ruler to measure how much rain is in the container. The depth of the water is how many inches (or centimeters) of rain fell on your area.

Now, imagine that your rain gauge shows one inch of rain. Just how much rain is that? One inch, right? Right, but what does that actually mean? It means that enough rain fell so that if all the water stayed, without running off or soaking in, the water would be one inch deep.

Lets think about how much water that really is. If your lawn is 75 feet deep and 100 feet wide, how much water fell on your lawn? 75 X 100 = 7500 square feet of lawn. Each square foot has 144 square inches (12 inches X 12 inches). 7500 square feet times 144 square inches tells us that you have 1,080,000 square inches in your lawn. If you got one inch of rain, then each square inch would have one inch of water, making it a cubic inch of water.

OK, so your lawn got 1,080,000 cubic inches of rain. There are 231 cubic inches in a gallon, so your lawn got 4675.3 gallons of rain! Each gallon of water weighs 8.34 pounds, which tells us that 38,992 pounds of rain fell on your lawn! That is 19.4 tons of water on your lawn.

You can try the same thing with a larger area. A square mile has 4,014,489,600 square inches. Divide that by 231 to get the number of gallons, which would be 17,378,742 gallons of water if you had one inch of rain. Multiply that by 8.34 and you find that 144,938,715 pounds of rain fell on that square mile.

OK, once you wrap your brain around that number, think about where all that water came from. The clouds! An average, fluffy white cloud can easily have more than 550 tons of water in it. Wait a minute! If clouds are that heavy, why don't they fall? The water is in very tiny droplets, small enough to be easily suspended by air currents. Each drop is very tiny, but when you add them all up, you get a tremendous amount of water. If you really want to stretch your mind, look at the size of a hurricane, and the amount of rain that it brings. Do a little math and you will get numbers that may be very hard to believe.

Have a wonder-filled week.