# Learn Stuff About How Science Works

What are the mechanics of flight? Why do the planets rotate? For the curious, these questions would be something to consider for hours, days, or years… before the Internet. Fortunately, now you can get the answers you are looking for in a few seconds and glut your curiosity.

1) Why does a stone skip across water instead of falling in?
As the stone moves over the water at a slight angle (ideally 20 degrees), the water actually creates a force upwards and backwards on the rock. These slow it down but at the same time push it into the air, so it bounces. The greater the velocity, the bigger the push.

2) Why do planes fly?
Simply put, planes fly by balancing the four forces that act upon them. Propelling the plane forward is thrust. Friction between the plane and the air, which pushes the plane back, is called drag. The weight of the plane pulls it down, and lift pushes the plane upwards. The wings of the plane are rounded on the bottom to create more pressure on the bottom than on the top. Thus, a part of the drag is converted to lift, and when lift overcomes weight, the plane rises.

3) How does a helicopter fly?
If you haven’t already, then take a moment to read the FAQ on planes to understand what thrust, drag, lift, and weight are. Helicopters work with the same forces, except that lift is created by the whirring blades on top of it. The controls allow the pilot to tilt the helicopter’s weight forward, backward, or sideways. In turn, the helicopter will accelerate in any one of these directions.

4) Why does a boomerang return?
A boomerang is shaped like a blade of a helicopter or plane wing in that one side (the one facing the ground) is rounded and produces more pressure than the other. This produces lift. Further, a boomerang has two parts that hinge around a central point. This hinge forces the boomerang to rotate when it is thrown. Then, like a helicopter, which tilts in one direction or another, the boomerang’s tilt produces the force that turns it back in a circle, toward the one who threw it.

5) What are the Northern Lights?
The Northern Lights, or Aurora Borealis are the result of protons and electrons coming from the Sun and reacting with molecules in the Earth’s atmosphere. These only occur near the poles, where the magnetic field of the Earth is too weak to deflect the protons and electrons.

6) Why is the sky blue instead of black?
White light is actually a combination of all colors, from red, to yellow, to green, to blue. When sunlight travels through the Earth’s atmosphere, the molecules in the atmosphere cause the different wavelengths to scatter, some of which are directed toward the surface of the Earth. We see blue light more than other wavelengths because blue light has the shortest wavelength and is therefore more likely to interact with molecules in the atmosphere.

7) How does a laser work?
Lasers are concentrated beams of light. They are formed by surrounding a crystal with mirrors, one of which is only a partially reflecting mirror. A light is shined on the crystal, which causes electrons from the crystal’s atoms to raise to a higher state and then fall to a lower state. When the electrons fall back, they release light. Then, the light bounces around the chamber, between the mirrors and other atoms, causing a chain reaction to build the power of the light. When the power is strong enough, it becomes too great for the partially reflecting mirror to contain and is emitted in a concentrated form.

8) Why are there seasons?
Contrary to what many people think, the seasons are not caused by the distance between the Earth and the Sun. Rather, they are due to the tilt of the Earth, which means that light does not make full contact with all areas of the Earth. When tilted away from the Sun, direct light hits the Southern Hemisphere. On the other side of the Sun, the tilt faces away, making it summer in the Northern Hemisphere.

9) How does global warming work?
Global warming is the effect of excess carbon dioxide and other greenhouse gases in the Earth’s atmosphere, which traps heat and causes the temperature to rise over time.

10) What is the ozone layer?
Ozone is comprised of three oxygen atoms, which form a highly unstable bond in the Earth’s atmosphere.

11) How does the odometer of a car work?
Mechanical odometers use gears to convert the rotations of car wheels into rotations of the odometer’s numbers. When the car runs in reverse, so does the odometer!

12) How does the speedometer of a car measure velocity?
A mechanical speedometer, or eddy current meter, uses magnetic force to push the needle on the gauge that the driver can see. The faster the wheels turn, the faster the magnet rotates, which creates more force, which, in turn, pushes the needle further up the gauge.

13) How does a gas gauge work?
There is a floater in the gas tank. As the fuel lowers, so does the floater. As the floater lowers, the amount of resistance increases, which reduces the current that goes to the gauge needle. The needle is a bimetallic strip, which is set to move from full to empty as the heat reduces. Gauges have been tweaked to show that they are full longer than they actually are, and show they are empty before they actually are.

14) Why do the planets orbit the Sun?
The Sun is so large that the force of its gravity is enough to keep the planets in orbit.

15) Why don’t the planets crash into the Sun?
Even though the Sun has a strong force, the planets rotate at a velocity around it, so that even though they are constantly being pulled toward it, this force is maintained in the speed of their orbits.

16) How was the solar system formed?
Scientists believe that a large cloud of dust and gas was disturbed by a nearby release of energy, possibly a supernova. The disturbance caused the collection of dust and gas to shrink, and as it shrunk, heat collected in the center and was lost toward the edges, due to laws of thermodynamics. The center eventually became the Sun, and other planets formed similarly, by aggregations of material further from the center.

17) How did the asteroid belt form?
Scientists believe that when the solar system formed, originally, there was a planet in between Mars and Jupiter. For reasons unknown, the planet collapsed, leaving debris and rubble where it stood. Asteroids are chunks of this debris.

18) What is a comet, and why do comets have tails?
A comet is a ball of ice, gas, and dust that is constantly shedding its materials. The gas and dust that falls off the comet forms the tail, which can be millions of miles long in some cases.

19) How does a steam engine work?
A steam engine works by heating a chamber with water in it. When the water boils, it places pressure on the chamber. The chamber is connected to pistons, so the excess pressure can do work on the pistons. The movement of the pistons is connected by way of gears to wheels.

20) How does a combustion engine work?
A combustion engine is very similar to a steam engine, except that instead of water in the chamber, there is a fuel. The fuel is ignited, and a miniature explosion does work on the pistons.