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Play arcade style review games like Crazy Taxi, Pacman and Soccer merged with trivia questions about SCIENCE REVIEW 68 to review and study for tests. Fun school game number 3967

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Wheel & Axle - Makes work easier by moving objects across distances. The wheel (or round end) turns with the axle (or cylindrical post) causing movement. On a wagon, for example, a container rests on top of the axle.

Inclined Plane - A flat surface (or plane) that is slanted, or inclined, so it can help move objects across distances. A common inclined plane is a ramp.

Wedge - Instead of using the smooth side of the inclined plane to make work easier, you can also use the pointed edges to do other kinds of work. When you use the edge to push things apart, this movable inclined plane is called a wedge. An ax blade is one example of a wedge.

Lever - Any tool that pries something loose is a lever. Levers can also lift objects. A lever is an arm that "pivots" (or turns) against a fulcrum (the point or support on which a lever pivots). Think of the claw end of a hammer that you use to pry nails loose; it's a lever. A see-saw is also a lever.

Pulley - Instead of an axle, a wheel could also rotate a rope, cord, or belt. This variation of the wheel and axle is the pulley. In a pulley, a cord wraps around a wheel. As the wheel rotates, the cord moves in either direction. Attach a hook to the cord, and now you can use the wheel's rotation to raise and lower objects, making work easier. On a flagpole, for example, a rope is attached to a pulley to raise and lower the flag more easily.

Screw - When you wrap an inclined plane around a cylinder, its sharp edge becomes another simple tool: a screw. If you put a metal screw beside a ramp, it may be hard to see similarities, but a screw is actually just another kind of inclined plane. One example of how a screw helps you do work is that it can be easily turned to move itself through a solid space like a block of wood.

Wheel and Axle

Inclined Plane

Wedge

Lever

Pulley

Screw

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The VEX Robotics Design System offers students an exciting platform for learning about areas rich with career opportunities spanning science, technology, engineering and math (STEM). These are just a few of the many fields students can explore by creating with VEX Robotics technology.

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In the 1600s, an English physicist and mathematician named Isaac Newton was sitting under an apple tree -- or so the legend tells us. Apparently, an apple fell on his head, and he started wondering why the apple was attracted to the ground in the first place.

Newton publicized his Theory of Universal Gravitation in the 1680s. It basically set forth the idea that gravity was a predictable force that acts on all matter in the universe, and is a function of both mass and distance. The theory states that each particle of matter attracts every other particle (for instance, the particles of " Earth" and the particles of "you") with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

So the farther apart the particles are, and/or the less massive the particles, the less the gravitational force.

The standard formula for the law of gravitation goes [source: UT]:

Gravitational force = (G * m1 * m2) / (d2)

where G is the gravitational constant, m1 and m2 are the masses of the two objects for which you are calculating the force, and d is the distance between the centers of gravity of the two masses.

G has the value of 6.67 x 10E-8 dyne * cm ²/gm ². So if you put two 1-gram objects 1 centimeter apart from one another, they will attract each other with the force of 6.67 x 10E-8 dyne. A dyne is equal to about 0.001 gram weight, meaning that if you have a dyne of force available, it can lift 0.001 grams in Earth's gravitational field. So 6.67 x 10E-8 dyne is a miniscule force.

When you deal with massive bodies like the Earth, however, which has a mass of 6E+24 kilograms (see How much does planet Earth weigh?), it adds up to a rather powerful gravitational force. That's why you're not floating around in space right now.

The force of gravity acting on an object is also that object's weight. When you step on a scale, the scale reads how much gravity is acting on your body. The formula to determine weight is [source: Kurtus]:

weight = m * g

where m is an object's mass, and g is the acceleration due to gravity. Acceleration due to gravity on Earth, is 9.8 m/s² -- it never changes, regardless of an object's mass. That's why if you were to drop a pebble, a book and a couch off a roof, they'd hit the ground at the same time.

For hundreds of years, Newton's theory of gravity pretty much stood alone in the scientific community. That changed in the early 1900s.

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Gravity is a force that we experience every minute of our lives, but hardly notice or give a passing thought to in our daily routines. Have you ever wondered what gravity is and how it works? Learn about the force of gravity in this article.

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Newton's Laws of Motion Website....From NASA

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Newton's Laws of Motion Website....From NASA

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This page is intended for college, high school, or middle school students. For younger students, a simpler explanation of the information on this page is available on the Kid's Page.

The motion of an aircraft through the air can be explained and described by physical principals discovered over 300 years ago by Sir Isaac Newton. Newton worked in many areas of mathematics and physics. He developed the theories of gravitation in 1666, when he was only 23 years old. Some twenty years later, in 1686, he presented his three laws of motion in the "Principia Mathematica Philosophiae Naturalis." The laws are shown above, and the application of these laws to aerodynamics are given on separate slides.

Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force. This is normally taken as the definition of inertia. The key point here is that if there is no net force acting on an object (if all the external forces cancel each other out) then the object will maintain a constant velocity. If that velocity is zero, then the object remains at rest. If an external force is applied, the velocity will change because of the force.

The second law explains how the velocity of an object changes when it is subjected to an external force. The law defines a force to be equal to change in momentum (mass times velocity) per change in time. Newton also developed the calculus of mathematics, and the "changes" expressed in the second law are most accurately defined in differential forms. (Calculus can also be used to determine the velocity and location variations experienced by an object subjected to an external force.) For an object with a constant mass m, the second law states that the force F is the product of an object's mass and its acceleration a:

F = m * a

For an external applied force, the change in velocity depends on the mass of the object. A force will cause a change in velocity; and likewise, a change in velocity will generate a force. The equation works both ways.

The third law states that for every action (force) in nature there is an equal and opposite reaction. In other words, if object A exerts a force on object B, then object B also exerts an equal force on object A. Notice that the forces are exerted on different objects. The third law can be used to explain the generation of lift by a wing and the production of thrust by a jet engine.

You can view a short movie of "Orville and Wilbur Wright" explaining how Newton's Laws of Motion described the flight of their aircraft. The movie file can be saved to your computer and viewed as a Podcast on your podcast player.
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Newton's Laws of Motion:

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Beginner's Guide Home Page

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This page is intended for college, high school, or middle school students. For younger students, a simpler explanation of the information on this page is available on the Kid's Page. The motion of an aircraft through the air can be explained and described by physical principals discovered over 300 years ago by Sir Isaac Newton.

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Electricity is related to charges, and both electrons and protons carry a charge. The amount of the charge is the same for each particle, but opposite in sign. Electrons carry a negative charge while protons carry positive charge. The objects around us contain billions and billions of atoms, and each atom contains many protons and electrons. The protons are located in the center of the atom, concentrated in a small area called the nucleus. The electrons are in motion outside of the nucleus in orbitals. The protons are basically trapped inside the nucleus and can't escape the nucleus. As a result, it is moving electrons that are primarily responsible for electricity.

There aren't a lot of places that you can see electricity. The most commonly- observed form of electricity is probably lightning. Lightning is a big spark that occurs when lots of electrons move from one place to another very quickly. There are three basic forms of lightning, cloud to cloud, cloud to surface, and surface to cloud. All are created when there is an unequal distribution of electrons. You can also see smaller sparks of electricity in science labs that contain Van de Graff generators, and can see even smaller arcs of electrons at home when you scuff your feet and then touch something like a metal doorknob (static electricity).

It's easy to see the uses of electricity around you. In fact, there are charges around your computer, your house, and your city. Electricity is constantly flowing through all of the wires in your town. There is also electricity in your flash light. That kind of electricity created by batteries is called direct current. The other major type is found in the outlets of your house. That household form of electricity is called alternating current.

Or search the sites for a specific topic.

Electricity and Magnetism (NASAConnect Video)

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Physics4Kids.com! This tutorial introduces electricity and magnetism in physics. Other sections include motion, heat, light, and modern physics.