Physical Science Final Study guide – Flashcards
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problem
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the purpose of the experiment
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hypothesis
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proposed solution; guessed answer - if, then statement or I think, because
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independent variable
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the factor you change in an experiment that causes a change
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dependent variable
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the measured variable that depends on the value of the independent variable
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conclusion
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the answer to the problem written as a statement
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K H Da B D C M
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use this chart to convert metric measurements
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motion
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a change in an object's position
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distance
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how far an object has moved
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displacement
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how far an object has moved from its original starting place
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instantaneous speed
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speed at any given point
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average speed
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total distance divided by total time
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balanced forces
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forces that are equal in size and opposite in direction; they do not move an object and the net force is equal to zero.
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unbalanced forces
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forces that are unequal in size and the direction is the same; they cause an object to move
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velocity
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the speed and direction of an object's motion; EX: 25 mph North
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The Law of Conservation of Momentum
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any time two or more objects interact they may exchange momentum but the total amount of momentum stays the same-momentum is conserved~p=m x v
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Newton's 1st Law of Motion
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an object in motion stays in motion and an object at rest stays at rest until a net force acts upon the object
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Newton's 2nd Law of Motion
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Force= mass x acceleration
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Newton's 3rd Law of Motion
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Forces always occur in pairs; the forces will always be equal and opposite
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friction
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a force that opposes motion between two surfaces that are touching each other; it slows down the motion of objects
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static friction
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friction between two surfaces that are not moving past each other
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sliding friction
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friction that opposes motion between two surfaces sliding past one another
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rolling friction
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friction between a rolling object and surface it rolls on
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Law of Gravitation
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Any two masses exert an attractive force on each other
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gravity
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one of the four basic forces that gives the universe its structure; the force of gravity depends on the mass and distance between the objects
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air resistance
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a type of friction that opposes the force of gravity
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mass
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the amount of matter in an object; stays the same no matter where you are
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weight
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the force of gravity pulling on a body; changes as gravitational force changes
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speed of gravity on Earth
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9.8 m/s2
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energy
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the ability to cause change
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three forms of energy
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kinetic, potential, mechanical
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kinetic energy
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energy in the form of motion; 1/2 mass x velocity(2)
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potential energy
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energy stored in a motionless object that gives it the potential to cause changes
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three types of potential energy
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elastic (rubber band), chemical (food), and gravitational (book on a shelf)
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mechanical energy
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the total amount of potential and kinetic energy in a system
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Law of Conservation of Energy
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Energy may change from one form to another, but the total amount of energy never changes
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power
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the amount of work done in a certain amount of time; the rate at which work is done; equals work divided by time and is measured in watts
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work
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the transfer of energy that occurs when a force makes an object move in the direction of the applied force; measured in joules (lifting weights, moving a desk)
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mechanical advantage
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the number of times a machine multiplies the effort force; not determined the same for all simple machines, depends on different things
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Units for energy, work, and power
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energy- joules, work- joules, power- watts
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lever
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bar that is free to pivot about a fixed point
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pulley
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grooved wheel with a rope, simple chain, or cable running along the groove
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wheel and axle
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machine with two wheels of different sizes rotating together
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inclined plane
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sloping surface that reduces the amount of force required to do work
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wedge
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inclined plane with one or two sloping sides that pushes things apart
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screw
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inclined plane wrapped around a cylindrical post
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fulcrum
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fixed point on a lever; the place where the lever rotates
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1st class lever
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fulcrum in the middle; see-saw, hammer, scissors
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2nd class lever
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fulcrum at the end, load in the middle; wheel barrow, car-jack
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3rd class lever
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fulcrum at the end, effort in the middle; tweezers, baseball bat
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temperature
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the average kinetic energy of an object's atoms or molecules
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heat
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thermal energy that flows from something warm to something cooler
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three methods of transferring thermal energy
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conduction, convection, radiation
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conduction
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direct contact (frying an egg, grilling meat)
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convection
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currents in liquids or gases (boiling pasta)
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radiation
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no medium required (sunlight, microwave)
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electrical insulator
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something that resists the flow of electricity (ex: wood)
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electrical conductor
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something that allows electricity to flow through it easily (ex: copper)
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static electricity
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the accumulation of excess electric charges on an object
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direct current
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Electrical current that flows in only one direction through a wire; found in batteries
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alternating current
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current in which electrons change direction at a regular rate and is used to run appliances
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resistance
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an electrical device that resists the flow of electrical current; measured in Ohms
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voltage
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the difference in electrical charge between two points in a circuit; measured in volts
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current
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a flow of electricity through a conductor; measured in amperes
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Ohm's Law
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I=V/R
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series circuit
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a circuit in which the objects are connected in a single path (holiday lights)
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parallel circuit
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circuit in which electric current can follow more than one path (house sockets)
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magnetic force
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interaction between two magnets - like poles repel and unlike attract
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magnetic pole
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the regions of a magnet where the magnetic force exerted by the magnet is strongest
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magnetic domain
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groups of atoms with aligned magnetic poles
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electromagnetism
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the connection between electricity and magnetism; magnetism produced by an electric current
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electromagnet
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temporary magnet made by passing an electric current through a wire coiled around an iron bar
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nuclear fission
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the process of splitting a nucleus into two nuclei with smaller masses
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nuclear fusion
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the process of two nuclei with low masses combining to form one nucleus of larger mass
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wave
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repeating disturbance or movement that transfers energy through matter or space
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mechanical wave
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waves that must travel through a medium
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electromagnetic waves
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waves that do not require a medium to travel through
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transverse waves
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matter in the medium moves at right angles to the direction the wave travels; made of crests and troughs
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compressional waves
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matter in the medium moves back and forth in the same direction the wave travels; made of compressions and rarefactions
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rarefaction
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less-dense region of compressional waves
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compression
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dense region of compressional waves
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reflection
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when a wave strikes an object and bounces off
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refraction
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the bending of a wave caused by a change in its speed as it moves from one medium to another
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interference
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when two or more waves overlap and combine to form a new wave
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diffraction
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when an object causes a wave to change direction and bend around it
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amplitude
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measure of energy carried by a wave
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wavelength
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distance between one point on a wave to the nearest point like it (crest to crest; compression to compression)
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crest
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highest point of a transverse wave
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trough
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lowest point of a transverse wave
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doppler effect
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change in the apparent frequency of a wave as observer and source move toward or away from each other
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opaque
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absorbs and reflects light; does not allow light to pass through it
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translucent
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some light passes through it
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transparent
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all light passes through it allows you to see through ex. glass
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law of reflection
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the angle of incidence is equal to the angle of reflection
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neon lights
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glass tubes filled with neon that produce light from electron collisions
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fluorescent lights
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When an electric current is passed through a tube, gas inside emits ultraviolet waves that cause a powder to glow
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mirror
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allows the reflection of an object to be seen; either a virual or real form
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lens
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transparent material with a curved surface that refracts light rays
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convex lens
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a curved lens in which the center is thicker than the edges so it converges light to the focal point
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concave lens
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a lens that is thicker at the edges than in the middle that bends light rays away from one another
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convex mirror
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a mirror that is curved outward like the back of a spoon; diverges to the focal point
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concave mirror
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a mirror that is curved inward like the inside of a spoon; converges to the focal point
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constant
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the parts of an experiment that stay the same
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Speed formula
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s=d/t
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Acceleration formula
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a=(final velocity - inital velocity)/time
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power formula
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power= work/time
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work formula
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work= force * distance
