# Physical Science Final Study guide

## 106 terms

### problem

the purpose of the experiment

### hypothesis

proposed solution; guessed answer - if, then statement or I think, because

### independent variable

the factor you change in an experiment that causes a change

### dependent variable

the measured variable that depends on the value of the independent variable

### conclusion

the answer to the problem written as a statement

### K H Da B D C M

use this chart to convert metric measurements

### motion

a change in an object's position

### distance

how far an object has moved

### displacement

how far an object has moved from its original starting place

### instantaneous speed

speed at any given point

### average speed

total distance divided by total time

### balanced forces

forces that are equal in size and opposite in direction; they do not move an object and the net force is equal to zero.

### unbalanced forces

forces that are unequal in size and the direction is the same; they cause an object to move

### velocity

the speed and direction of an object's motion; EX: 25 mph North

### The Law of Conservation of Momentum

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

### Newton's 1st Law of Motion

an object in motion stays in motion and an object at rest stays at rest until a net force acts upon the object

### Newton's 2nd Law of Motion

Force= mass x acceleration

### Newton's 3rd Law of Motion

Forces always occur in pairs; the forces will always be equal and opposite

### friction

a force that opposes motion between two surfaces that are touching each other; it slows down the motion of objects

### static friction

friction between two surfaces that are not moving past each other

### sliding friction

friction that opposes motion between two surfaces sliding past one another

### rolling friction

friction between a rolling object and surface it rolls on

### Law of Gravitation

Any two masses exert an attractive force on each other

### gravity

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

### air resistance

a type of friction that opposes the force of gravity

### mass

the amount of matter in an object; stays the same no matter where you are

### weight

the force of gravity pulling on a body; changes as gravitational force changes

9.8 m/s2

### energy

the ability to cause change

### three forms of energy

kinetic, potential, mechanical

### kinetic energy

energy in the form of motion; 1/2 mass x velocity(2)

### potential energy

energy stored in a motionless object that gives it the potential to cause changes

### three types of potential energy

elastic (rubber band), chemical (food), and gravitational (book on a shelf)

### mechanical energy

the total amount of potential and kinetic energy in a system

### Law of Conservation of Energy

Energy may change from one form to another, but the total amount of energy never changes

### power

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

### work

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)

the number of times a machine multiplies the effort force; not determined the same for all simple machines, depends on different things

### Units for energy, work, and power

energy- joules, work- joules, power- watts

### lever

bar that is free to pivot about a fixed point

### pulley

grooved wheel with a rope, simple chain, or cable running along the groove

### wheel and axle

machine with two wheels of different sizes rotating together

### inclined plane

sloping surface that reduces the amount of force required to do work

### wedge

inclined plane with one or two sloping sides that pushes things apart

### screw

inclined plane wrapped around a cylindrical post

### fulcrum

fixed point on a lever; the place where the lever rotates

### 1st class lever

fulcrum in the middle; see-saw, hammer, scissors

### 2nd class lever

fulcrum at the end, load in the middle; wheel barrow, car-jack

### 3rd class lever

fulcrum at the end, effort in the middle; tweezers, baseball bat

### temperature

the average kinetic energy of an object's atoms or molecules

### heat

thermal energy that flows from something warm to something cooler

### conduction

direct contact (frying an egg, grilling meat)

### convection

currents in liquids or gases (boiling pasta)

no medium required (sunlight, microwave)

### electrical insulator

something that resists the flow of electricity (ex: wood)

### electrical conductor

something that allows electricity to flow through it easily (ex: copper)

### static electricity

the accumulation of excess electric charges on an object

### direct current

Electrical current that flows in only one direction through a wire; found in batteries

### alternating current

current in which electrons change direction at a regular rate and is used to run appliances

### resistance

an electrical device that resists the flow of electrical current; measured in Ohms

### voltage

the difference in electrical charge between two points in a circuit; measured in volts

### current

a flow of electricity through a conductor; measured in amperes

I=V/R

### series circuit

a circuit in which the objects are connected in a single path (holiday lights)

### parallel circuit

circuit in which electric current can follow more than one path (house sockets)

### magnetic force

interaction between two magnets - like poles repel and unlike attract

### magnetic pole

the regions of a magnet where the magnetic force exerted by the magnet is strongest

### magnetic domain

groups of atoms with aligned magnetic poles

### electromagnetism

the connection between electricity and magnetism; magnetism produced by an electric current

### electromagnet

temporary magnet made by passing an electric current through a wire coiled around an iron bar

### nuclear fission

the process of splitting a nucleus into two nuclei with smaller masses

### nuclear fusion

the process of two nuclei with low masses combining to form one nucleus of larger mass

### wave

repeating disturbance or movement that transfers energy through matter or space

### mechanical wave

waves that must travel through a medium

### electromagnetic waves

waves that do not require a medium to travel through

### transverse waves

matter in the medium moves at right angles to the direction the wave travels; made of crests and troughs

### compressional waves

matter in the medium moves back and forth in the same direction the wave travels; made of compressions and rarefactions

### rarefaction

less-dense region of compressional waves

### compression

dense region of compressional waves

### reflection

when a wave strikes an object and bounces off

### refraction

the bending of a wave caused by a change in its speed as it moves from one medium to another

### interference

when two or more waves overlap and combine to form a new wave

### diffraction

when an object causes a wave to change direction and bend around it

### amplitude

measure of energy carried by a wave

### wavelength

distance between one point on a wave to the nearest point like it (crest to crest; compression to compression)

### crest

highest point of a transverse wave

### trough

lowest point of a transverse wave

### doppler effect

change in the apparent frequency of a wave as observer and source move toward or away from each other

### opaque

absorbs and reflects light; does not allow light to pass through it

### translucent

some light passes through it

### transparent

all light passes through it (see through ex. glass)

### law of reflection

the angle of incidence is equal to the angle of reflection

### neon lights

glass tubes filled with neon that produce light from electron collisions

### fluorescent lights

When an electric current is passed through a tube, gas inside emits ultraviolet waves that cause a powder to glow

### mirror

allows the reflection of an object to be seen; either a virual or real form

### lens

transparent material with a curved surface that refracts light rays

### convex lens

a curved lens in which the center is thicker than the edges so it converges light to the focal point

### concave lens

a lens that is thicker at the edges than in the middle that bends light rays away from one another

### convex mirror

a mirror that is curved outward like the back of a spoon; diverges to the focal point

### concave mirror

a mirror that is curved inward like the inside of a spoon; converges to the focal point

### constant

the parts of an experiment that stay the same

s=d/t

### Acceleration formula

a=(final velocity - inital velocity)/time

power= work/time

### work formula

work= force * distance