acceleration
ate at which an object's velocity changes with time; the change in velocity may be in magnitude (speed), or direction, or both.
Acceleration =
change of velocity/time interval
air resistance
Friction, or drag, that acts on something moving through air.
angular momentum
Product of a body's rotational inertia and rotational velocity about a particular axis. For an object that is small compared with the radial distance, it is the product of mass, speed, and radial distance of rotation.
Angular momentum = mvr
center of gravity (CG)
Point at the center of an object's weight distribution, where the force of gravity can be considered to act.
center of mass
Point at the center of an object's mass distribution, where all its mass can be considered to be concentrated. For everyday conditions, it is the same as the center of gravity.
centrifugal force
Apparent outward force on a rotating or revolving body.
centripetal force
Center-directed force that causes an object to follow a curved or circular path. This changes the direction of velocity not it's magnitude i.e. speed. Although it moves in an object in a circle an Actual force must be provided for this force
conservation of energy
Principle that energy cannot be created or destroyed. It may be transformed from one form into another, but the total amount of energy never changes.
conservation of momentum
In the absence of a net external force, the momentum of an object or system of objects is unchanged.
mv(before event) = mv(after event)
Energy
That which can change the condition of matter. Commonly defined as the ability to do work; actually only describable by examples.
equilibrium rule
?F = 0. On an object or system of objects in mechanical equilibrium, the sum of forces equals zero. Also, ?? = 0; the sum of the torques equal zero.
Escape Velocity
Velocity that a projectile, space probe, etc. must reach to escape the gravitational influence of Earth or the celestial body to which it is attracted.
Force
Any influence that tends to accelerate an object; a push or pull; measured in newtons. Force is a vector quantity.
Frame of reference
Vantage point (usually a set of coordinate axes) with respect to which position and motion may be described.
Friction
Force that acts to resist the relative motion (or attempted motion) of objects or materials that are in contact.
Gravity
Attraction between objects due to mass. See also law of universal gravitation and universal gravitational constant.
Gravitational potential energy
PE = mgh
Energy associated with a gravitational field, which on Earth results from the gravitational interaction of a body and Earth Potential energy (PE) then equals mass (m) times the acceleration due to gravity (g) times height (h) from a reference lev
Heat
The energy that flows from one object to another by virtue of a difference in temperature; measured in calories or joules.
Impulse
Product of force and the time interval during which the force acts. Impulse produces change in momentum.
Impulse = Ft = ?(mv)
Inertia
Sluggishness or apparent resistance of an object to change its state of motion. Mass is the measure of inertia.
inelastic
Term applied to a material that does not return to its original shape after it has been stretched or compressed.
inertial frame of reference
Unaccelerated vantage point in which Newton's laws hold exactly.
Joule
SI unit of work and of all other forms of energy. One joule of work is done when a force of 1 newton is exerted on an object moved 1 meter in the direction of the force.
Elastic collision
Collision in which colliding objects rebound without lasting deformation or heat generation.
kilograms
Fundamental SI unit of mass. It is equal to 1000 grams
Kinetic energy (KE)
Energy of motion, equal (nonrelativistically) to mass multiplied by the square of the speed, multiplied by the constant 1/2.
KE = �mv2
Law of conservation of momentum
In the absence of an external force, the momentum of a system remains unchanged. Hence, the momentum before an event involving only internal forces is equal to the momentum after the event:
mv(before event) = mv(after event)
Law of universal gravitation
For any pair of objects, each particle attracts the other object with a force that is directly proportional to the product of the masses of the objects, and inversely proportional to the square of the distance between them (or their centers of mass if sph
Lift
In application of Bernoulli's principle, the net upward force produced by the difference between upward and downward pressures. When lift equals weight, horizontal flight is possible.
Mass
Quantity of matter in an object; the measurement of the inertia or sluggishness that an object exhibits in response to any effort made to start it, stop it, or change in any way its state of motion; a form of energy.
Net Force
Combination of all the forces that act on an object.
Newton's 2nd law of motion
The acceleration produced by a net force on an object is directly proportional to the magnitude of the net force, is in the same direction as the net force, and is inversely proportional to the mass of the object.
Newton's 1st law of motion
Every object continues in a state of rest, or of uniform speed in a straight line, unless acted on by a nonzero net force. Also known as the law of inertia.
Newton's 3rd law of motion
Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.
Normal Force
Component of support force perpendicular to a supporting surface. For an object resting on a horizontal surface, it is the upward force that balances the weight of the object.
Period
In general, the time required to complete a single cycle. (a) For orbital motion, the time required for a complete orbit
1st Postulates of special relativity
All laws of nature are the same in all uniformly moving frames of reference.
2nd Postulate of special relativity
The speed of light in free space has the same measured value regardless of the motion of the source or the motion of the observer; that is, the speed of light is invariant.
Potential Energy
Energy of position, usually related to the relative position of two things, such as a stone and Earth (gravitational PE)
Power
Rate at which work is done or energy is transformed, equal to the work done or energy transformed divided by time; measured in watts. Power= Work/ Time
Projectile
Any object that moves through the air or through space, acted on only by gravity (and air resistance, if any).
Rotational Inertia
Reluctance or apparent resistance of an object to change its state of rotation, determined by the distribution of the mass of the object and the location of the axis of rotation or revolution.
Rotational Speed
Number of rotations or revolutions per unit of time; often measured in rotations or revolutions per second or minute.
Rotational Velocity
Rotational speed together with a direction for the axis of rotation or revolution.
Speed
How fast something moves; the distance an object travels per unit of time; the magnitude of velocity.
Speed = Distance / Time
Suppourt Force
Upward force that balances the weight of an object on a surface.
Tangential Speed
Linear speed along a curved path.
Tangential Velocity
Component of velocity tangent to the trajectory of a projectile.
Tangent
Line that touches a curve in one place only and is parallel to the curve at that point.
Vector Quantity
Quantity in physics that has both magnitude and direction. Examples are force, velocity, acceleration, torque, and electric and magnetic fields.
Weight
The force that an object exerts on a supporting surface (or, if suspended, in a supporting string)�often, but not always, due to the force of gravity.
Work-Energy Theorem
Work done on an object is equal to the kinetic energy gained by the object
Work = ?KE
Linear Momentum
Product of the mass and the velocity of an object. Also called momentum. (This definition applies at speeds much less than the speed of light.)
Linear Motion
Straight-line motion, as opposed to circular, angular, or rotational motion.
Momentum
Inertia in motion. The product of the mass and the velocity of an object (provided the speed is much less than the speed of light). Has magnitude and direction and therefore is a vector quantity. Also called linear momentum, and abbreviated p.
p = mv
Average Speed
Path distance divided by time interval.
Average speed =
Total distance covered/Time interval
Universal gravitational constant
The proportionality constant G that measures the strength of gravity in the equation for Newton's law of universal gravitation. F = G m1m2/ d2
Law of Simultaneity
Occurring at the same time. In special relativity, two events that are simultaneous in one frame of reference can have a different time and distance from a different time of reference (perspective).
Displacement
the difference between the initial position and the final position of an object.
Sliding Friction
Contact force produced by the rubbing together of the surface of a moving object with the material over which it slides.
Static Friction
Force between two objects at relative rest by virtue of contact that tends to oppose sliding.
Inelastic
Term applied to a material that does not return to its original shape after it has been stretched or compressed.
Length Contraction
Shrinkage of space, and therefore of matter, in a frame of reference moving at relativistic speeds.
The Twin Paradox
An effect predicted by the general theory of relativity: if one of a pair of twins remains on Earth, and the other travels in a rocket at a speed near the speed of light, the traveling twin will be younger than the earthbound twin upon returning to Earth.
The Speed of light
Is a constant usually denoted by the letter c. It is the speed of all electromagnetic radiation, including visible light, in free space. It is the speed of anything having zero rest mass.
Instantaneous Speed
Speed at any instant.