Ionosphere

Ionosphere

What is it?

The ionosphere is the layer of the earth's atmosphere starting around 70 or 80 kilometers above the earth's surface and extending up indefinitely. The ionosphere is above the mesosphere. The thermosphere is part of the ionosphere.

Give me an example!

The ionosphere is mostly composed of gasses that have been ionized by ultraviolet radiation from the sun and is jam-packed full of free electrons (not attached to atoms). But the coolest thing about the ionosphere is that it reflects radio transmissions, making it possible to bounce radio waves off of it and communicate with people in other hemispheres!

Thermosphere

Thermosphere

What is it?

The thermosphere is the layer of the earth's atmosphere that lies above the mesosphere at altitudes between 80 and 200 kilometers above the earth's surface. The thermosphere is also the lower part of the ionosphere.

Give me an example!

The lower levels of the thermosphere are composed of molecules of nitrogen (N and N2) and Oxygen (O and O2). The higher you go in the thermosphere, the warmer the temperature becomes because solar radiation is absorbed by oxygen molecules.

Mesosphere

Mesosphere

What is it?

The mesosphere is the layer of the earth's atmosphere that extends from an altitude of 50 kilometers up to 80 kilometers above the earth's surface. The mesosphere is above the stratosphere and below the thermosphere.

Give me an example!

The temperature in the mesosphere starts out at 0 degrees Celsius in its lowest regions and decreases in the upper regions to -100 degrees Celsius. The only people who have ever been in the mesosphere are astronauts!

Stratosphere

Stratosphere

What is it?

The stratosphere is the layer of the earth's atmosphere that exists between approximately 15 and 50 kilometers above the earth's surface. The stratosphere is between the troposphere and the mesosphere.

Give me an example!

Conditions in the stratosphere are not affected by the water cycle or any other earthly changes in weather. Temperatures in the stratosphere start at about -50 degrees Celsius at the bottom and climb to around 0 degrees Celsius in the upper parts. The stratosphere also contains the earth's fragile ozone layer which has been damaged by chloroflourocarbons.

Troposphere

Troposphere

What is it?

The troposphere is the lowest layer of the earth's atmosphere. The troposphere extends from the surface of the earth to between 10 and 12 miles up (or 10 to 20 kilometers).

Give me an example!

The troposphere is where all our weather happens! Water molecules moving through the water cycle do their thing within the troposphere. That's a whole lot of evaporation, condensation, and percipitation (rain, sleet, hail, and snow)! The level level of the earth's atmosphere directly above the troposphere (called the stratosphere) forms a barrier that keeps the earth's moisture from escaping. The ceiling of the troposphere is higher over the Equator than at the Poles, and it is higher over the Poles in summer than in winter.

Atmosphere

Atmosphere

What is it?

The atmosphere is the mass of air surrounding the Earth.

Give me an example!

There are many layers of atmosphere: Troposphere, Stratosphere, Mesosphere, Thermosphere.

Surface

Surface

What is it?

A surface is the exterior or upper boundary of an object. It is the external part or layer of something.

Give me an example!

The part of a window pane I can touch is its surface!

Area

Area

What is it?

In general, an area is a particular extent of space or surface. It can even refer to the scope of a concept or an activity!

In mathematics, an area is the surface included within a set of lines, or the number of unit squares equal in measure to the specific surface.

Give me an example!

The formula for calculating the area of a rectangle is height multiplied by width!

Arc

Arc

What is it?

Arcs can be shaped like a bow, a curve, or an arch. Mathematicians define them as any unbroken part of a circle or other curved line. Others favor the simplified version, a segment of a curve.

Give me an example!

Beautiful rainbows often appear in the sky. They provide an excellent example of an arc.

Aquifer

Aquifer

What is it?

An aquifer is underground bed or layer yielding ground water for wells and springs.

Give me an example!

In order to get water to flow up the surface of the earth a well needs to hit an aquifer. Until the drill reaches this underground layer of water, the well will be dry.

Applied Force

Applied Force

What is it?

An applied force is a pushing or a pulling ( bending, compression, and tension ) that act on the outside of an object.

Give me an example!

It is important for scientists to be able to identify the applied forces that are acting on an object! A bridge experiencing too much compression may collapse!

Angular Speed

Angular Speed

What is it?

Angular speed is the speed of a rotating body.

Give me an example!

Angular speed is measured in the number of complete turns a spinning wheel or top makes in one minute. This is expressed as revolutions (spins) per minute, or RPM.

Have you ever seen a tachometer in a car? Tachometers measure the number of RPMs the crankshaft of the engine is doing -- in other words, the speed of the motor, not the speed of the wheels. This helps drivers know when to shift gears to make the most efficient use of the motor's output as RPMs change.

Angular Momentum

Angular Momentum

What is it?

Angular momentum is the force that keeps a spinning body spinning.

Give me an example!

Have you ever spun a gyroscope? Remember how once it is spinning, it tends to continue spinning? The force of gravity combines with rotational speed to produce angular momentum that keeps the gyroscope spinning.

Angular Velocity

Angular Velocity

What is it?

Angular velocity is the velocity of an object which is in rotary motion. Angular velocity is measured in radians per second.

Give me an example!

Imagine a washer tied to a string that is swinging around in a circle (rotary motion). If you swing the washer at a constant velocity, you should be able to calculate how far it moves around the circle in one second of time. Then you could take the number of degrees of that angle and multiply it by pi radians per 180 degrees to find the angular velocity.

Angular Acceleration

Angular Acceleration

What is it?

Angular acceleration is a change in angular velocity.

Give me an example!

When a driver pushes down on the accelerator pedal in an automobile, more fuel is sent to the engine, which ultimately changes the angular velocity of the wheels. This angular acceleration in turn makes the car go faster.

Angle

Angle

What is it?

An angle is a place where two straight lines come together.

Give me an example!

Have you ever looked at the corner of a picture frame or window where two parts of the frame meet? These two straight lines form an angle!

Algorithm

Algorithm

What is it?

An algorithm is a set of mathematical instructions that must be followed in a fixed order. If the algorithm is given to a computer, the computer will calculate an answer to a mathematical problem using the algorithm.

Give me an example!

Algorithms are often used as the way to read something that had been encrypted by some encryption software.

Average

Average

What is it?

A mathematical average is the sum of a group of numbers, divided by the number of numbers in the group.

Give me an example!

Have you ever wondered how teachers determine what the average score was on a test? First they take all the scores and add them together. Then they divide that number by the number of scores. The result is the average test score!

Algebra

Algebra

What is it?

Algebra is the branch of mathematics dealing with the study of number systems! Algebra uses letters and other symbols to describe general properties of numbers, to specify conditions placed on them, or to describe relationships between them!

Give me an example!

The common number systems within Algebra include the natural numbers, the integers (including zero and the negatives of the counting numbers), the rational numbers (fractions), the real numbers (decimals), and the complex numbers (like 2 - 4i).

Albert Einstein

Albert Einstein

What is it?

Albert Einstein (1879-1955) was a physicist who proposed the theory of relativity, and made many steps towards our understanding of the universe.

Give me an example!

Einstein examined the phenomenon of energy emitting from radiating objects in discrete quantities, and discovered that the energy of these quanta was directly proportional to the frequency of the radiation. Einstein proposed the special theory of relativity, and in 1905, Einstein showed how mass and energy were equivalent. Whew…what a busy scientist! He was said to have been so into his work, that he didn't have time to comb his hair!

Acute Angle

Acute Angle

What is it?

In mathematics, an acute angle is any angle measuring less than 90 degrees.

Give me an example!

The open space made when two chopsticks touch while eating is an example of an acute angle.

Acceleration Due To Gravity

Acceleration Due To Gravity

What is it?

Acceleration due to Gravity is the acceleration that acts on all objects that fall within the Earth's gravitational field. As an object falls, gravity pulls it to Earth at a rate of 9.81 meters per second per second. That is, for every second that an object falls, its speed increases by 9.81 meters per second.
(This holds true in the absence of air resistance at sea level)


Give me an example!
Sky divers experience the Acceleration due to Gravity as soon as they jump from the airplane. For an instant they have zero vertical speed, then gravity accelerates them toward the ground. Their speed increases at the rate of 9.81 meters per second for each second that they fall, until they open their parachute, increasing their drag and slowing their descent to Earth.

Absolute Zero

Absolute Zero

What is it?

Absolute zero is the temperature at which no known system can still engage in heat transfer. Absolute zero is the temperature where all molecular motion ceases.

On a Kelvin thermometer, absolute zero is simply "zero." On a Celsius thermometer, absolute zero is at -273 degrees. Absolute zero is the lowest temperature in the world, and has never actually been attained in a laboratory.

Give me an example!

When you freeze water into ice, the molecules form a solid crystalline structure and move much less than when the water is in its liquid phase. If you continue to lower the temperature of the ice, you will reach a point where all molecular motion comes to a standstill - theoretically, at absolute zero.

Absolute Temperature

Absolute Temperature

What is it?

An absolute temperature scale is one that has absolute zero as its zero.

Give me an example!

The Kelvin temperature scale is an example of an absolute temperature scale. Its zero is at absolute zero, the theoretical temperature 273 Celsius degrees below the freezing point of water. Absolute zero is the temperature where all molecular motion ceases.

Addition of Vectors

Addition of Vectors

What is it?

The addition of vectors is how you determine the total effect of all the forces at work on an object. When all the vectors are added, you end up with a single vector that shows the overall combined effect.

Give me an example!

Have you ever ridden a bicycle when you caught a tailwind? You suddenly didn't have to pedal as hard because the vector of your velocity on the bicycle was suddenly added to the vector of the wind. Now imagine if you suddenly caught a headwind. The opposite would be true - you would have to pedal harder because you would be adding vectors with opposite directions.

Mathematical Model

What is it?
Mathematical models are equations, inequalities, functions, or other mathematical expressions that model a real-world process.

Give me an example!

Realistic mathematical models are increasingly important, especially with the use of computers! Many processes, which formerly could only be studied by expensive laboratory experiments, can now be studied as realistic mathematical models!

Cohesion & Adhesion

Cohesion: Due to inter-molecule attraction, liquids can with-stand slight tension. the inter-,olecule attration is known as Cohesion.

Adhesion: Cohesion is between molecules of the same fluid whereas adhesion is the property by which molecules of differrent fluids are attracted to one another or molecules of a fluid are attracted to by molecules of a solid. Liquids stick to the wall of vessel by the property of adhesion.

Capillaries

Capillaries

What is it?

Capillaries lie between the arteries which carry blood from the heart and veins carrying blood back to the heart. Gases like oxygen and carbon dioxide as well as important metabolic materials that travel by diffusion across the membranes of capillaries into the body.

Give me an example!

Capillaries are the interface between the circulatory system and the tissues of the body itself. There are beds of capillaries throughout your body, in fact there is at least one capillary within I/100th of a millimeter of each of the cells in your body!

Wavelength

Wavelength

What is it?

Wavelength is the distance between the starting and ending point of one cycle of a wave.

Give me an example!

Have you ever watched waves crashing on the shore? The distance between the crest of one wave and the crest of the next one is one wavelength.

Cohesion (chemistry)

Cohesion (n. lat. cohaerere "stick or stay together") or cohesive attraction or cohesive force is the action or property of like molecules sticking together, being mutually attractive. This is an intrinsic property of a substance that is caused by the shape and structure of its molecules which makes the distribution of orbiting electrons irregular when molecules get close to one another, creating electrical attraction that can maintain a macroscopic structure such as a water drop.

Mercury in a glass flask is a good example of the effects of the ratio between cohesive and adhesive forces. Because of its high cohesion and low adhesion to the glass, mercury does not spread out to cover the bottom of the flask, and if enough is placed in the flask to cover the bottom, it exhibits a strongly convex meniscus, where the meniscus of water is concave . Mercury will not wet the glass, unlike water and many other liquids,^[1] and if the glass is tipped, it will 'roll' around inside.

Adhesive

Adhesive
What is it?

An adhesive is a substance that binds two other substances together.

Give me an example!

Have you ever used tape to connect two pieces of paper? Then you have used an adhesive! The sticky stuff on the tape is the adhesive that holds the two pieces of paper together. Glues are also adhesives because they can hold two things together.

Mathematics

What is it?
Mathematics is the science of patterns and order. It involves the study of measurement, properties, and relationships of quantities using numbers and symbols.

Give me an example!
Geometry is one branch of mathematics that involves the study of shapes!

Wind Energy

Wind Energy

What is it?

Wind energy is produced when the wind moves the fins of a wind generator to turn a shaft and operate a pump or generator. Wind energy is a renewable resource and can reduce our dependence on fossil fuels.

Give me an example!

Have you ever seen a picture of Holland that shows windmills? Their giant blades are turned by wind energy. In the old days, this wind energy was used to turn mill wheels and grind grain into flour.

Propulsion

Propulsion

What is it?

Propulsion is when a body is moved in some direction because force is applied to it.

Give me an example!

Propulsion can come from many different sources. Wind energy pressing against a sail moves boats through water. Thrust from a jet engine provides propulsion to aircraft. Mechanical energy generated by an internal combustion engine moves an automobile.

Buoyancy

Buoyancy

What is it?

Buoyancy is the force that keeps a floating object from sinking.

Positive buoyancy is the tendency to float upward. Negative buoyancy is the tendency to sink toward the bottom. Neutral buoyancy is when an object maintains a relatively stable position, not going up or down.

Give me an example!

Have you ever watched a leaf floating in the water? The leaf floats because of buoyancy. The force of the surface tension of the water pushing up against the leaf is greater than the force of gravity pulling down on the mass of the leaf.

Components of Forces

Components of Forces

What is it?

Components of forces are the many different vector quantity(s) that make up the complex forces acting on an object.

Give me an example!

Have you ever seen a boat sail against a tide? The components of forces acting on the boat are very complex. Gravity pulls the boat down on the surface of the water, and buoyancy pushes up on the boat from underneath. The boat's own propulsion (from a sail, motor, or oars) pushes it in one direction (a vector), and the current of the tide pushes the boat in another direction (another vector). The directional motion of the boat is the sum of all four of these forces.

The Bernoulli Principle

the Bernoulli Principle

What is it?

Bernoulli's Principle is a law of physics that has to do with gasses (such as air) and liquids (like water). It states that when the velocity (speed) of a gas or liquid is increased, its pressure becomes lower.

Give me an example!

When air rushes over the curved top of an aircraft wing, it goes faster than when it passes over the flat bottom of the wing. Therefore, the pressure or force of the air pressing down on the top of the wing becomes less than the force of the air pressing up on the bottom of the wing. The result is lift, one of the Four Forces of Flight.

Lift

Lift

What is it?

Lift is the force that makes an airplane wing or helicopter rotor rise and helps the aircraft escape the pull of the earth (gravity). Lift is a product of differences in air pressure and is based on the Bernoulli Principle.

Give me an example!

Have you ever noticed how a hawk soars effortlessly in circles in the sky on a summer afternoon? The hawk is giving his wings a rest by taking a free ride on rising, heated columns of air called thermals that provide lift.

Thrust

Thrust

What is it?

Thrust is the force that moves objects forward. Without thrust, we would never go anywhere! Thrust is also the opposite force to drag, which tries to keep objects from moving forward.

Give me an example!

Have you ever thrown a dart or paper airplane? The force imparted on the dart or airplane by your arm is thrust that moves it forward. In aircraft and rockets, thrust is provided by the backdraft of a turning propeller or by the pressure created by superheated gasses escaping from the combustion chamber of a jet engine. After lift makes an aircraft airborne, thrust is what moves it through the air like when you throw a paper airplane. In most aircraft, the direction of thrust is controlled by flaps called rudders and ailerons.

Drag

Drag

What is it?

Drag is the opposite of thrust. Drag must be overcome in order for an aircraft (or anything else, for that matter) to move forward through a gas or liquid. Other terms for drag are wind resistance and friction.

Drag, when using a computer, is when you hold down the mouse button while moving an object or icon.

Give me an example!

Have you ever noticed that you can go faster down a steep hill on your bike if you hunch down closer to the handlebars? That's because you're lowering your wind resistance, or drag. Modern aircraft and automobiles are designed to overcome drag by being aerodynamic in shape. The less friction air encounters when moving over the outer surface of an object, the faster the object can move with the same amount of thrust.