Liftoff to Learning: Toys in Space 2

Glossary of Science Terms,
Principles and Mathematical
Equations

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The following terms, scientific principles and mathematical equations are useful in describing the actions of toys on Earth and in space. It is recommended that you refer to physical science or physics textbooks for detailed explanations of terms, principles and equations with which you are unfamiliar.

Acceleration - This is the rate of change in velocity.

Action Force - This is a force exerted on an object.

Air Resistance - This is the force of the air pushing against a moving object.

Amplitude - This is the distance that a moving wave rises or falls above or below its rest position.

Angular Momentum - This is a property of spinning motion that must be conserved. Angular momentum is the product of an object's mass, the radius of its circular path, and its velocity.

The angular momentum of a spinning object is equal to its moment of inertia times its angular velocity. If the resultant external torque acting on a system is zero, the total angular momentum of the system is constant. The angular momentum is greater when the mass is farther from the rotation axis as in the spinning disk of a gyroscope. The direction of the angular momentum of a spinning object is along the axis of rotation in a direction defined by the right hand rule. When the curled fingers point in the direction of the rotation, the direction of the angular momentum is that of the outstretched thumb.

Bernoulli's Principle - In a flowing fluid, increases in its velocity are accompanied by a decrease in its pressure. Bernoulli's Principle applies to all fluids including liquids.

Buoyancy - This is an upward force exerted on an object in a liquid equal to the weight of the liquid which the object displaces. Microgravity is a neutral buoyancy condition.

Center of Mass - This is the point at which the entire mass of an object is centered.

Centrifugal Force - This is the apparent outward force exerted by an object moving in a circle. In reality, the object is simply trying to move in a straight line.

Mario Runco watches his police car leave the track after its forward motion became zero.

Centripetal Force - This is the inward force which causes an object to turn.

Centripetal Force = mass x velocity2/r

Circular Motion - A force is required to change the direction of the velocity of an object which is moving in a circle. This inward force is called a centripetal force. Without an inward centripetal force, the object would move outward in straight line motion.

Collision: Elastic and Inelastic - For perfectly elastic collisions, the relative speed of recession after the collision equals the relative speed of approach before the collision. In a perfectly inelastic collision, there is no relative speed after the collision, the objects remain together. All other collisions lie between these two extremes.

Compression - This is a concentration of particles in a longitudinal wave.

Conservation of Energy - The amount of energy in a closed system remains constant over time.

Conservation of Momentum - The conservation of momentum is equivalent to Newton's third law of motion: for two objects subject only to their mutual interactions, the sum of the momenta of the objects remains constant in time.

Also note that momentum is a vector quantity and the momenta of objects must be added vectorally.

Crest - This is the high point in a wave.

Drag - Drag is the resistant force exerted by a fluid (such as the air) when an object moves through it. The drag force opposes the motion of the object.

Elastic Potential Energy - This term is used to describe the energy stored in a stretched object (usually a spring).

Energy - This is a property of nature that is present in many forms. Energy that moves from one system to another under the action of forces is called work.

Force - This is a push or pull.

Freefall - This is the condition of an object falling in a gravity field

Frequency - This is the number of waves or pulses passing a point per unit time.

Friction - This is a force which opposes sliding motion.

When two bodies are in contact with each other, they exert forces on each other due to the interaction of the particles in one body with those of the other. The tangential component of the contact force exerted by one object on another is called a frictional force.

Mission specialist Don McMonagie prepares to release three Gravitrons connected to a wiffle ball.	Mission specialist Susan Helms tries to make "ringers" with the horseshoes.

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