Think you know your science? Take this quick quiz and find out. But be warned--some of these questions aren't as simple as they sound . . . . :)
1. Which force is greater:
(a) the gravitational force exerted upon you by the Earth
(b) the gravitational force exerted upon the Earth by you
(c) the two gravitational forces are the same
2. Which of these statements is true:
(a) time flows more slowly on the top floor of a tall building
(b) time flows more slowly on the bottom floor of a tall building
(c) time flows the same at both places
3. If you fire a rifle bullet straight out horizontally from the top of a tall tower standing on a horizontal surface, and at the very same instant drop an identical rifle bullet from the top of the same tower, which bullet hits the surface first?
(a) they both hit at the same time
(b) the one fired horizontally hits first
(c) the one dropped vertically hits first
4. Which has more bones in its body, a shark or a lobster?
(a) both have the same number of bones
(b) the shark has more bones
(c) the lobster has more bones
5. You are flipping a coin, and just flipped eight "heads" in a row. Which of the following is true:
(a) the probability of the next flip producing another "heads" is greater than 50%
(b) the probability of the next flip producing another "heads" is exactly 50%
(c) the probability of the next flip producing another "heads" is less than 50%
6. Which of these animals is not venomous:
(a) poison dart frog
(b) Komodo dragon
(c) duck-billed platypus
7. Which has more vertebral bones in its neck:
(a) a giraffe
(c) a sloth
8. The Earth's atmosphere contains mostly:
(a) carbon dioxide
9. The surface temperature of a yellow star is:
(a) hotter than the surface temperature of a blue star
(b) hotter than the surface temperature of a red star
(c) the same as the surface temperature of a blue or red star
10. Which statement is true:
(a) the Sun revolves around the Earth
(b) the Earth revolves around the Sun
(c) neither of these statements is true
Answers and explanations below the orange thingamajig . . .
1. The answer is (c). The force is the same. Gravity is not directional. The gravitational force each member of the pair exerts on the other is the same in either direction. So why does the Earth pull you down, and you don't pull the Earth up? Actually, you do pull the Earth up, but only by an imperceptible amount. Acceleration is proportional to "force" divided by "mass". Since you have a very small mass, the Earth's gravitational force on you produces a large acceleration for you (which you feel as gravity), but because the Earth has such a large mass, when you exert the same gravitational force on the Earth, you produce in it only a very tiny acceleration.
2. The answer is (b). Time flows more slowly on the bottom floor. Under the principle of relativity, time flows more slowly (to an outside observer) in a stronger gravitational field than it does in a weaker one, and the closer you are to the center of the earth, the stronger the earth's gravitational field is. This has been confirmed by experiments using very sensitive identical atomic clocks on the ground and in the air. The effect is vanishingly small (unnoticeable by us) but it is real and measurable.
3. The answer is (a). They both hit at the same time. The force of gravity produces a vertical acceleration that is independent of the horizontal. It doesn't matter at what speed the bullet moves horizontally--gravity still pulls it down at the same acceleration (1 "g", or 32 feet per second per second).
4. The answer is (a). They both have the same number of bones--zero. Lobsters are invertebrates and do not have any internal skeleton. Sharks, though, belong to the group of very ancient cartilaginous fishes called Chondrichthyes, dating back over 450 million years ago. Their skeletons are made entirely of cartilage--sharks have no bones.
5. the answer is (b). The probability of a "heads" is exactly 50%. In a series of random events, the odds of any particular event are not at all affected by previous results. The chance of getting a "heads" in a particular coin toss is always 50-50, no matter what happened before.
6. the answer is (a). The poison dart frog is not venomous. "Venomous" refers to an animal's ability to inject poison into another animal, while "poisonous" refers to an animal's ability to poison another animal that eats it. In other words, a venomous animal is only dangerous if it bites you, while a poisonous animal is only dangerous if you bite it. Although the poison dart frog, like many other amphibians, has strong toxins in its skin, it has no way to inject those toxins into another animal. It is not venomous. Komodo dragons, however, have venomous saliva injected into its prey with its teeth, and duck-billed platypus have venom glands which they can inject into an attacker using sharp spurs on their hind feet.
7. The answer is (c). The sloth. Both you and a giraffe each have seven vertebral bones in your neck. In fact, nearly all mammals have seven vertebrae in their neck. But there are a few exceptions: manatees and two-toed sloths have only six, while three-toed sloths have eight and sometimes nine. Nobody is really sure why--it seems to be just a genetic quirk that doesn't have any effect on the sloth.
8. The answer is (c). Nitrogen. Earth's atmosphere contains 78% nitrogen, 21% oxygen, and 1% other gases (mostly argon, at 0.9%). Carbon dioxide makes up only 0.04% of the Earth's atmosphere. The rest is gases like hydrogen, helium, krypton, neon, and xenon.
9. The answer is (b). A yellow star is hotter than a red star. The temperature of a star is related to the wavelengths of the light it emits--the shorter the wavelength, the hotter the star. So star temperatures range from red/orange (the coolest), to yellow, to blue/white (the hottest).
10. The answer is (c). Neither of these statements is true. You thought this one was easy, didn't you? Actually it is sort of a trick question. Copernicus was right--the Sun does not revolve around the Earth. But the scientific reality is that the Earth does not revolve around the Sun either--they actually both revolve around a common shared center of gravity, called a "barycenter". If two orbiting celestial objects have equal mass, their barycenter will be halfway between them, and they will both orbit around that point. Because the Sun is so much larger than the Earth though (indeed the Sun contains more than 99.8% of all the mass in the solar system), their center of gravity is very much closer to the Sun, making the Earth sweep out a very wide arc as it orbits around that point and the Sun make a very small one. In fact, to be really accurate, every object in the solar system, including the Sun itself, revolves around the center of gravity of the entire solar system--a point which lies slightly outside of the Sun's surface. This makes the Sun itself wobble very slightly back and forth in space as it orbits around this common center of gravity. This principle is used by astronomers to detect planetary systems around distant stars by measuring their wobble.
So how did you do? :)