


Liftoff to Learning: Toys in Space 2
Glossary of Science Terms,
Principles and Mathematical
Equations
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.


