REX'S EMAIL about PHYSICS |
In a message dated 2/6/98 01:52:37, you wrote: <<Dear Rex, I wrote you last month for the first time and I got a response. Thank you. My mom helps me write these questions because I am just six years old. I am in kindergarten now. I want to know how come we can sometimes see a Rainbow when the sun is shining and the rain is coming down. The beanie named Rainbow helped me come up with this question. I looked for a rainbow yesterday when the sun was shining and it was raining but I could not find one. I am Kellie and I live in Quinton, Va if I am the winnng question for the month of June. Thanks so much for having such an informative site. I am also watching lots of tad poles get bigger. They are on top of my pool cover. How long before they turn into frogs? Kellie in VA. Age 6>>
Hello Kellie,
Rainbows are formed when the sunlight passes through some rain droplets. It doesn't have to be actually raining where you are, but somewhere between you and the Sun, which should be shining (= not totally cloudy). The water droplets act as little "prisms" that bend or "refract" the light waves into different wavelengths, and each wavelength (measured in Angström units) has its own color.
An easy way to remember the colors is by the funny name ROY G. BIV = red, orange, yellow, green, blue, indigo and violet.
The tadpoles should already be jumping around in your pool! It only usually takes a couple weeks, depending on the kind of frog.
REX
In a message dated 8/5/98 01:22:02, you wrote: <<My name is Rick and I am 11 years old. I live in Phoenix, Arizona. My question is what kind of energy is used to run a roller coaster? Your friend, Rick>>
Hello Rick,
Well, let's see now. The roller coaster is probably powered by electricity = ELECTRICAL energy. This may come from burning fossil fuels such as coal or oil= CHEMICAL energy changed to heat or THERMAL energy, an atomic power plant = ATOMIC energy, running water over a hydroelectric dam = FLOWING WATER energy, a series of windmill type contraptions = WIND energy, solar cells = SOLAR energy, and there are probably more possibilities!
This electrical energy is translated into MECHANICAL energy when the sprockets of the chain begin to pull the cars up the first incline.
At the top of the hill the POTENTIAL energy of the cars changes to KINETIC energy which is due to the pull of the force of GRAVITY energy. Gravity is the result of the ATOMIC DENSITY energies which collected some of the dense elements at the Earths core due to the CENTRIPETAL spinning energy of the primordial planet which in turn was caused by the CONDENSATION nucleus energy of our proto-solar system whose ROTATION energy was a spin off of the EXPLOSIVE energy of the Big Bang.
The screams you may do as the cars fall are produced by chemical-electrical NERVE energy causing moving AIR energy to vibrate your vocal cords which is simple VIBRATION energy.
When you get off the ride and have thought about all of these possible forms of energy, you will probably need more energy to continue your day and head for the nearest FAST-FOOD energy center! More energy to you!!
Princess is just sitting here with her mouth wide open thinking about all of this! She says I have too much BATTY energy!!
REX
In a message dated 22/4/98 04:33:20, you wrote: <<Hi, I was hoping you could answer this. It is not for school, but I am really curious... Okay say you are riding a motor cycle and you drop a pen. Since you are in motion, you leave the pen behind. So what I don't understand is when you are riding on the bus, and drop a pen, the bus is moving so why doesn't the pen drop a few inches (or feet) away from where you dropped it? Thanks for your time! Dawn in Maryland>>
Hello Dawn,
This question is almost philosophically scientific! I had to ask Hoot, the symbol of wisdom, to help me with this one!
When you are on the bike, the pen is dropped in the street and falls downward at the usual acceleration due to the pull of gravity PLUS the velocity you are riding at. Its path would be a curve not a straight line and it would land behind your bike.
Inside the bus, you AND all parts of the bus AND the pen are all travelling at the same velocity. SO, when you drop the pen to the floor, the pen and the floor are also moving at the exact same rate, and the pen drops straight down.
I bet if you drop the pen out of the bus window, it would fall in the same way as when you dropped it from the motorcycle. AND, if you carefully dropped it onto the footboard of the bike while moving at 20 miles and hour it would land right straight onto that flat surface. UNLESS the wind pushed it!! Do the experiment and see.
See how complicated these things can be-- and how simple at the same time!!
REX
In a message dated 28/1/98 03:57:35, you wrote: <<Dear Rex, Did Isic Newton relly develope the laws of gravity by an apple falling on his head or did he study it for a long time. Then did he just write it down in a book or tell everyone about it and rumors just spread. Jason Adams >>
Hello Jason,
The apple didn't really fall on Sir Issac Newton's head! He saw an apple and other things fall, and wondered why they always fall downwards. He thought that there must be some reason. Just like you do when you see something-- you ask why? You too are a scientist. You have to practice at it to become good though.
Being a mathematician, someone who like to play with numbers, he figured out the "Law of Gravitation" and lectured about it at the university and also published a book on it in Latin, titled "Principia". Do you know when the first book was made, in what language and what its title was?
REX
In a message dated 10/1/98 04:19:27, you wrote: <<Hey Rex,
Wow, this is a pretty cool home that you have here on the internet.
Well, anyways, when I grow up, I want to be a person who studys rocks. This is probably an easy question for you, but I would like to know what that is called. Also, in science, we are studying kinetic and potential energy. In potential energy, I'm really confused about it. In school, we did an egg drop where an egg is wrapped in a vehicle of our choice and dropped from multiple feet in the air. When it falls, it potential or kinetic energy being demonstrated?? Confused =0 >>
Dear Confused,
The name of the science that studys rocks is called Petrology. And if you only want to study the minerals in the rocks, that is Mineralogy.
I had to ask Quackers about your egg question. She is our expert on egg dropping.
You already know that you can change one korm of energy into another. An example would be changing electrical energy into heat energy when you plug in a toaster and toast some bread with it. Solar cells can change light energy into electrical energy.
She says that when the egg is not moving, that is called potential energy. Kinetic means to move, so when the egg actually drops it is an example of kinetic energy or energy in motion. When you drop it, the egg changes its potential energy into kinetic energy.
She wants to know what kind of vehicle you chose to wrap your egg in? Was it a van or a station wagon? She really likes vans because in a van she and the rest of us Beanies have lots of room to play and all.
REX
In a message dated 9/1/98 00:59:25, you wrote: <<Question:
What is the formula for the momentum of an object? Do you know the formula for the acceleration of an object? Sorry but i need to know this for school.>>
Hi,
Well, you ALMOST had me shaking my head and saying "no way"! But then I remembered my friend Speedy, who knows all about speed and motion. After all, he is the one who ran the race with the hare, remember the story? And Speedy won!!
So Speedy took me away from the computer for a couple hours and explained what momentum was on the blackboard we have here in the nursery. So here it is:
If we have a hormongous dinosaur like my Dad, Big REX, and a teensy mouse like Trap running at the same velocity, let's say up the street at 10 miles an hour, which has the most momentum? It is really a simple answer. Ask yourself which weighs more, or as scientists say, which one has the most mass? Of course, the dinosaur has the most mass, so my Dad also has the most momentum! Speedy told me that the formula for is Momentum = Mass x Velocity.
Acceleration is another form of motion. Actually Speedy is typing this now because my friend REX is still a little confused about momentum and he is taking time out to work on some problems I gave him to do.
An example is the easiest way to explain it. I am standing at the end of a long street, meaning that I am not moving, which would be zero velocity. Then I begin running as fast as I can for 10 minutes. At the end of the 10 minutes I am moving at 85 miles an hour. That tells you that I am now moving faster after a certain amount of time. That is what scientists call accelaration. The formula would be Acceleration = change in velocity divided by time.
OK, REX is back. WOW, all my answers to Speedy's quiz questions are correct!! I got 100!! Hope you did too! Speedy is such a good teacher!
REX