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Science For Exam
Vocabulary
Question | Answer |
---|---|
Scientific Method | hypothesis, prediction, experimental outcome |
Fact | close aggreement between observers with a series of observations of the same phenomenon |
Hypothesis | educated guess |
Law | hypothesis that is tested over and over, not contradicted |
Theory | sythesis that is well-tested and verified hypothesis about certain espects of natural world |
Force | push or pull |
Net Force | combination of all forces acting on an object |
vector | an arrow that represents the magnitude and direction of a quanity |
Vector Quanity | quanity that needs both magnitude and direction |
Scalar Quanity | can be described with magnitude only |
Mechanical Equilibrium | no physical changes occur |
Equilibrium Rule | net force is zero, object is in mechanical equilibrium |
Support Force | upward force that balances weight of object on a surface |
Resultant | sum of two or more vectors |
Friction | acts between materials that touch as they move past each other |
Inertia | property of a body to resist change in a state of motion |
Newton's First Law (Law of Inertia) | every object continues in a state of rest or of uniform speed in a straight line, unless acted on by a nonzero net force |
Kilograms | fundamental unit of mass |
Mass | quanity of matter in an object |
Weight | force of gravity on an object |
Newton | SI unit of force |
Relative | motion of one object with respect to another |
Speed | how fast an object is moving |
Instantaneous Speed | spread of an object at any instant in time |
Average Speed | total distance covered divided by time |
Velocity | speed in any given direction |
Accerleration | rate at which the velocity is changing |
Free Fall | moving under the infulence of the gravitional force only is said to be in this |
Elapsed Time | time that has elapsed or passed since the beginning of any motion |
Components | two vectors at right anges that add up to a given vector |
Resolution | process of determining components of a vector |
Projectile | any object that moves through air or space, acted on only by gravity (or air resistance, if any) |
Inversely | two values change in opposite directions |
Newton's Second Law | describes relationship among an object's mass, and object's acceleration, and the net force on the object |
Fluid | both liquids and gases because they flow |
Air Resistance | friction acting on something moving through air |
Free-Body Diagram | showing all the forces acting on an object |
Pressure | amount of force per unit of area |
Pascal | newtons per square meter that measure pressure |
Terminal Speed | speed at which the acceleration of a falling object is zero because friction balances the weight |
Terminal Velocity | terminal speed together with the direction of motion |
Interaction | when objects present action upon each other |
Newton's Third Law | whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object |
Action Force | one force in an interaction |
Reaction Force | other force in an interaction |
Momentum | inertia in motion |
Impulse | change in momentum |
Law of conservation | in the absence of an external force, momentum of a system remains unchanged |
Elastic Collision | when objects collide without deforming or gernerating heat |
Inelastic Collison | collison in which colliding objects become distorted and generate heat |
Work | th product of the net force on an object and the distance throught which the object is moved |
Joule | unit of work |
Power | rate at which work is done |
Watt | unit of power |
Energy | property of an object or sytem that enables it to do work |
Mechanical Energy | energy due to position of something or the movement of something |
Potential Energy | energy that is stored by virtue of its position |
Kinetic Energy | energy of motion |
Work-Energy Theorem | relationship between work and energy |
Law of Conservation of Energy | energy can't be created or destroyed. Can be transformed from one form into another, but total amount of energy never changes |
Machine | device used to multiply forces or simply to change direction of forces |
Lever | simple machine made of a bar that turns about a fixed point |
Fulcrum | pivot point |
Mechanical Advantage | the ration of output force to input force for a machine |
Pulley | kind of lever that can be used to change the direction of a force |
Effciency | ratio of useful energy output to total energy input |
Fuel Cell | hydrogen and oxygen gas are compressed at electrodes to produce water and electric current |
Vibration | repeating, back-and-forth motion about an equilibrium position |
Wave | disturbance that is transmitted progressively from one place to the next with no actual transport of matter |
Period | time back-and-forth swing of a pendulum |
Simple Harmonic Motion | back-and-forth vibratory motion of a pendulum |
Sine Curve | pictorial representation of a wave |
Crest | high points of a wave |
Trough | low points of a wave |
Amplitude | distance from midpoint to a crest in a wave |
Wavelength | distance from crest to crest |
Frequency | number of vibrationsan object makes in a unit of time |
Hertz | unit of frequency |
Transverse Wave | whenever the motion of the medium is at right angles to the direction in chich a wave travels |
Longitudinal Wave | when the particles oscillate parallel to or along the direction of the wave |
Interference pattern | regular arrangment of places where wave effects are increased, decreased or neutralized |
Constructive interference | crest of one wave overlaps the crest of another and their individual effects add together |
Destructive interference | crest of one wave overlaps the crest of another and their individual effects are reduced |
Out of phase | crests of one wave overlap troughs of another to produce regions of zero amplitude |
In phase | crests of one wave overlap the crests of the other and the troughs overlap as well |
Standing Wave | wave that appears to stay in one place, or doesn't sem to move throught the medium |
Node | the stationary points of a standing wave |
Antinode | positions on a standing wave with the largest amplitudes are known |
Doppler Effect | apparent change in frequency due to the motinon of the source |
Blue Shift | an increase in frequency |
Red Shift | decrease in frequency |
Bow Wave | crests overlap at the edges in a v shape |
Shock Wave | three-dimensional wave that consists of overlapping spheres that form a cone |
Sonic Boom | sharp crack heard when the shock wave that sweeps behind a supersonic aircraft reaches the listeners |
Pitch | peoples' subjective about frequency of sound |
Infrasonic | sound waves with frequencies below 20 hertz |
Ultrasonic | sound waves with frequencies above 20 hertz |
Conpression | region of condensed waves |
Rarefraction | region of the wave that is spread apart |
Natural Frequency | object vibrates when it is disturbed |
Forced Vibration | object is made to vibrate by another vibrating object that is nearby |
Resonance | phenomenon that occurs when frequency of vibration forced on an object matches the object's natural frequency and dramatic increase in amplitude occurs |
Photon | massless bundles of concentrated electromagnetic energy |
Light Year | distance light travels in one year |
Electromagnetic Waves | energy traveling in waves that is partly electric and partly magnetic |
Electromagnetic Spectrum | range of electromagnetic waves |
Infrared | frequencies lower than the red of visible ligh |
Ultraviolet | heat lamps give these off, frequencies higher than violet (sunburn) |
Transparent | materials that transmit ligh |
Opaque | materials that block light |
Ray | thin beam of light |
Shadow | region formed where light can not reach |
Umbra | total shadow |
Penumbra | partial shadow where light from a different angle is overlapping the region of shadow |