# Stories tagged speed of light

Aug
16
2007

## Again with the odds and ends questions

A cross section of the neck area: In this faithful reproduction of a lithograph plate from Gray's Anatomy (the book, not the TV show), the epiglottis is clearly shown.
So, if you’ve been following along with my previous posts (there must be someone who can’t wait for “Joe” to make another post…hi mom) I am the person at the Science Museum who collects the paper questions for the Scientist on the Spot. Some questions are really funny, some are totally random, a lot of people want to know where babies come from and some are just good questions that have simple answers. Here are a bunch of questions that are of that last type.

Q: What is dry ice made of?
A: Dry ice is solid carbon dioxide. I didn’t know this until just now - the term “dry ice” is a generalized trademark, meaning it is a brand name that has become the general term for a product – like Kleenex. Also cool about dry ice is that is goes through sublimation at room temperature – meaning it goes straight from a solid to a gas.

Q: Why can’t you breathe and swallow at the same time?
A: Because of the amazing epiglottis. The epiglottis is a flap in your throat that normally points up (allowing you to breathe), but during the act of swallowing it flops down and covers the trachea and directs food down to the esophagus. The picture above should make it all clear.

Q: How fast is light?
A: 1,079,252,848.8 kilometers per hour. Very, very fast.

Q: What causes the force between two charged particles, i.e. why does Coulomb’s Law work?
A: Coulomb’s Law simply states,

The magnitude of the electrostatic force between two point charges is directly proportional to the product of the magnitudes of each charge and inversely proportional to the square of the distance between the charges.

Yeah, I have no idea, though these people seem to know the answer.

Q: Why do we have shadows?
A: You can guess the age of the visitor asking this question both by the type of question and by their handwriting. I can just imagine a parent saying, “I don’t know why we have shadows Maria, why don’t you ask the scientist?” Anyway, we have shadows when we block a source of light from getting directly to a place. So when I am standing on the sidewalk on a sunny day, part of me is blocking the light of the sun and the part that is blocked is the shadow. Vampires don’t have shadows, but since this is a science blog I feel obligated to also mention that vampires don’t exist. Which I guess makes it true that they don’t have shadows then…