# Physical Science Vocab

## 118 terms

### Inertia

The sluggishness or apparent resistance an object offers to change in its state of motion.

### Speed

Distance traveled per time

### Velocity

the speed of an object and specification of its direction of motion.

### Acceleration

rate at which velocity changes with time; the change in velocity may be in magnitude or direction or both

### Free Fall

state of fall free from air resistance and other forces except for gravity.

### Mass

The quantity of matter in an object

### Weight

The gravitational force exerted on an object by the nearest most-massive body

### Kilogram

the fundamental SI unit of mass. One kilogram is the amount of mass in 1 liter of water

### Newton

the SI unit of force. One Newton is the force that will give an object of mass 1 kg an acceleration of 1 m/s squared

### Volume

The quantity of space an object occupies

### Force

any influence that can cause an object to be accelerated, measured in Newton's

### Mechanical Equilibrium

the state of an object or system of objects for which any impressed forces cancel to zero and no acceleration occurs.

### Static Equilibrium

an object that is not moving and has 0 acceleration.

### Dynamic Equilibrium

an object that is moving, without accelerating.

### Friction

the resistive forces that arise to oppose the motion or attempted motion of an object past another with which is in contact.

### Terminal Speed

the speed at which the acceleration of a falling object terminates because friction balances the weight.

### Momentum

the product of the mass of an object and its velocity.

### Impulse

the product of the forces acting on an object and the time during which it acts.

### Relationship of Impulse and Momentum

impulse is equal to the change in the momentum of the object that the impulse acts on.

### Conservation of Momentum

when no external net force acts on an object or system of objects, no change of momentum takes place.

### Elastic Collision

collision in which colliding objects rebound without lasting deformation or the generation of heat

### Inelastic Collision

a collision in which the colliding objects become distorted and generates heat during the collision.

### Newtons 1st Law

Every object continues in a state of rest, or in a state of motion in a straight line at a constant speed, unless it is compelled to change that stare by forces exerted upon it.

### Newtons 2nd Law

The acceleration produced by a net force on an object is directly proportional to the net force, and is inversely proportional to the mass of the object.

### Newtons 3rd Law

Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object.

### Interaction

Mutual action between objects in which each one exerts an equal and opposite force on the other.

### Force Pair

The action and reaction pair of forces that constitute an interaction.

### Force Vector

An arrow drawn to scale so that its length represent the magnitude of a force and its direction of the force.

### Velocity Vector

an arrow drawn to scale so that its length represents the magnitude of the velocity and its direction represents the direction of motion.

### Resultant

the net force of a combination of two or more vectors.

### Vector Components

parts into which a vector can be separated and that act indifferent directions from the vector.

### Net Force

the combination of all forces that act on an object.

### Vector Quantity

A quantity that specifies direction and magnitude.

### Support Foce

the force that supports an object against gravity, sometimes called normal force.

### Friction

The resistive force that opposes the motion or attempted motion of an object through a fluid or past another object with which it is in contact.

### Air Resistance

The force of friction acting on an object due to its motion through air.

### Hang Time

The time that one's feet are off the ground during a vertical jump.

### The Law Of Universal Gravititation

every mass in the universe attracts every other mass with a force that for two masses is directly proportional to the product of their masses and inversely proportional to the square of the distance separation them.

### Inverse Square Law

a law relating the intensity of an effect to the inverse square of the distance from the cause.

### Weightlessness

a condition encountered in free-fall wherein a support force in lacking.

### Work

the product of the force and the distance through which the force moves

### Power

The rate time of work

### Energy

the property of a system the that enables it to do work

### Potential Energy

the stored energy that a body possesses because of its position

Energy of Motion

### Conservation of Energy

energy cannot be created or destroyed

### Conservation of Energy Machines

the work output of any machine cannot exceed the work input

### Efficiency

the percent of the work put into a machine that is converted into useful work output.

### Conductivity

the transfer and distribution of heat energy that moves from molecule to molecule within a substance

### Convection

the transfer of heat energy in a gas or liquid by means of currents in the heated fluid

the transfer of energy at the speed of light by means of electronic waves.

### Newtons Law Of Cooling

the rate of loss of heat with time from an object is proportional to the excess temperature of the substance over the temperature of its surroundings

### Green House Effect

the heating effect of a medium such as glass or the earth's atmosphere that is transparent to the short-wavelength radiation of sunlight but opaque to long-wavelength terrestrial radiation

### Thermodynamics

the study of heat and its transformation to other form of energy

### Absolute Zero

the lowest possible temperature that a substance may have

### Thermal Energy

the total of the molecular energies - kinetic energy and potential energy- internal to a substance.

### First Law Of Thermodynamics

a restatement of the law of energy conservation, usually as it applies to a system involving changes in temperature

a process, usually of expansion or compression, wherein no heat enters of leaves a system

### Second Law Of Thermodynamics

heat will never spontaneously flow from a cold object to a hot object.

### Hot Engine

a device that changes thermal energy to mechanical work

### Evaporation

the change of phase at the surface of a liquid as it passes to the gaseous phase

### Condensation

the change of phase form gas to liquid

### Temperature

a measure of the hotness and coldness of substances, related to the average kinetic energy per molecule in a substance, measured in degrees Celsius or Fahrenheit or in Kelvin's.

### Heat

the thermal energy that flows from a substance of higher temperature to a substance of lower temperature, commonly measured in calories or joules.

### Specific Heat Capacity

the quantity of heat per unit mass required to raise the temperature of a substance by 1 Celsius degree.

### Boiling

the rapid state of evaporation that takes place within the liquid as well as at its surface.

### Sublimation

the process of changing phase from a solid to a gas without passing through the liguid phase (dry ice)

### Heat Of Fusion

The amount of energy to change phase from solid to liquid (and vice versa.)

### Heat Of Vaporization

The amount of energy required to change phase from liquid to gas (and vice versa.)

### Sine Curve

A wave form traced by simple harmonic motion.

### Amplitude

For a wave or vibration, the maximum displacement on either side of the equilibrium (midpoint) position.

### Wavelength

The distance between successive crests, troughs, or identical parts of a wave.

### Frequency

For a vibrating body or medium, the number of vibrations per unit time.

### Hertz

The SI unit of frequency.

### Period

the time required for a vibration or a wave to make a complete cycle; equal to 1/frequency.

### Wave Speed

The speed with which waves pass a particular point: wave speed=frequency X wavelength.

### Transverse Wave

A wave in which the medium vibrates in a direction perpendicular (transverse) to the direction in which the wave travels.

### Longitudinal Wave

A wave in which the medium vibrates in a direction parallel (longitudinal) with the direction in which the wave travels.

### Compression

Condensed region of the medium through which a longitudinal wave travels.

### Rarefaction

Rarefied region of the medium through which a longitudinal wave travels.

### Interference Pattern

The pattern formed by superposition of different sets of waves, which produces mutual reinforcement in some places and cancellation in others.

### Standing Wave

A stationary wave pattern formed in a medium when two sets of identical waves pass through the medium in opposite directions.

### Doppler Effect

The change in frequency of wave motion resulting in motion of the sender or the receiver.

### Bow Wave

The V-shaped wave made by an object moving across a liquid surface at a speed greater than the wave speed.

### Shock Wave

the cone-shaped wave made by an object moving at supersonic speed through a fluid.

### Sonic Boom

The loud sound resulting from a shock wave.

### Infrasonic

Describes a sound of frequency too low to be heard by the normal human ear----below 20 hertz.

### Ultra Sonic

Describes a sound of a frequency too high to be heard by the normal human ear---above 20,000 hertz.

Reechoed Sound

### Refraction

The bending of a wave, either through a non-uniform medium or from one medium to another, caused by differences in wave speed.

### Forced Vibration

The setting up of vibrations in an object by a vibrating force.

### Natural Frequency

A frequency at which an elastic object naturally tends to vibrate, so that minimum energy is required to produce a forced vibration or to continue vibration at the frequency.

### Fundamental Frequency

The lowest frequency of vibration, or the first harmonic. In a string, the vibration makes a single segment.

### Resonance

The response of a body when a forcing frequency matches it natural frequency.

### Beats

A series of alternate reinforcements and cancellations produced by the interference of two waves of slightly different frequency, heard as a throbbing effect in sound waves.

### Quality

The characteristics timbre of a musical sound.

### Partial Tone

One of the frequencies present in complex tone.

### Harmonic

A partial tone that is an integer multiple of the fundamental frequency.

### Electromagnetic Wave

An energy-carrying wave emitted by vibrating electrical charges (often electrons) and composed of oscillating electric and magnetic fields that regenerate one another.

### Electromagnetic Spectrum

The range of electromagnetic waves that extends in frequency from radio waves to gamma rays.

### Transparent

The term applied to materials through which light can pass in straight lines.

The three colors—red, blue, and green.

### Subtractive Primary Colors

the three colors of absorbing pigments---magenta, yellow, and cyan.

### Complementary Colors

Any two colors that, when added, will produce white light.

### Diffraction

The bending of light that passes around an obstacle.

### Interference

The result of superposing different waves of the same wavelength. Constructive interference results from crest-to-crest reinforcement; destructive interference results from crest-to-through cancellation.

### Polarization

The alignment of the transverse electric vectors that make up electromagnetic radiation.

### Reflection

The return of light rays from a surface in such a way that the angle at which a given ray is returned is equal to the angle at which it strikes the surface.

### Refraction

The bending of an oblique ray of light when it passes from one transparent medium to another.

### Law Of Reflection

The angle of incidence equals the angle of reflection.

### Critical Angle

The minimum angle of incidence inside a medium at which a light ray is totally reflected.

### Total Internal Reflection

The total reflection of light raveling within a medium that strikes the boundary of another medium at an angle at, or greater than, the critical angle.

### Converging Lens

A lens that is thicker in the middle than at the edges.

### Diverging Lens

A lens that is thinner in the middle than at the edges.

### Virtual Image

An image formed by light rays that do not converge at the location of the image.

### Real Image

An image formed by light rays that converge at the location of the image.

### Aberrations

Limitations on the formation of perfect images, which are inherent, to some degree, in all optical systems.

### Photoelectric Effect

The emission of electrons from a metal surface when light shines on it.

Example: