TO THE CENTER/ DUAN WARSYNSKI
Mr. La Mont, since I was a child I have been a fan of science fiction and I still cherish the first book I received with all the works of Jules Verne. Over the course of my life I have seen movies like Journey to the Center of the Earth and others, and I have always been curious about a more realistic opinion, more based on science and less on fiction.
Can you tell me what would happen if we could really get to the center of the Earth, could we continue until we reached the other side?
R. Don Duan, we share this same taste for those works by Jules Verne, which still nourish us now.
Suppose you put on some kind of futuristic suit that protects you from all effects of pressure, all effects of heat, all effects of toxic gases, and all effects of radiation. So what happens when you jump into the hole? You accelerate as you fall, gaining speed due to the earth’s gravity. After about ten seconds, having traveled 0.5 kilometers (0.008% of the way to the center of the Earth), a top speed of about 200 kilometers per hour (120 mph) is reached. The air resistance at this speed is high enough to prevent you from accelerating any further. The further you fall, the weaker gravity becomes because more and more of the Earth’s mass is above you, canceling out the gravity on the other side of the Earth. Also, as you fall, the air pressure increases so that the air exerts more force against your movement. With gravity getting weaker and air resistance getting stronger, your speed is constantly decreasing.
After a week or so of falling (with a top speed of 200 km/h, it takes you a while to go the 6,400 km to the center), you finally arrive at the exact center of the Earth. The force of gravity at the center of the Earth is zero because there are equal amounts of matter in all directions, all exerting an equal gravitational pull. Also, the air in the hole is so dense at this point that it’s like traveling through soup. The small amount of momentum you have at this point will cause you to overshoot the center of the Earth and keep moving through the hole. But once you pass the center of the Earth, “down” is now in the other direction, so you slow down and reverse direction before going much further than the center.
You continually fall toward the center of the Earth, pass it under your own power, and then fall back in the other direction. This motion is a lot like a yo-yo or a kid on a playground swing continually going over the low point. With such thick air, you eventually lose momentum and stop your yo-yo movement around the center of the Earth: you end up stuck floating in the center of the Earth. Good trip, and good luck.
SWEET WATER
Where in the world are the largest freshwater deposits found?
A. Brazil has the highest freshwater resources in the world, representing approximately 12% of the world’s freshwater resources. It’s just because the Amazon region of this country contains 70% of Brazil’s total fresh water. Russia has the second largest fresh water reserve, which is about 1/5 of the world’s fresh water.
