Download Study Guide for Final

Study Guide for Final
Scientific Theory – an explanation for many hypotheses and observations
Scientific Law – a summary of many experimental results and observations. A law tells you how something works, not why.
Observation - the process of obtaining information by using the senses
Hypothesis - a possible explanation or answer to a question: it must be testable
Matter - anything that has mass and takes up space
Volume - the amount of space taken up by an object
Density of liquids
A. In a liquid, the denser layers will sink to the bottom
B. If the density of an object is less than the density of water it will float
Mass - a measure of the amount of matter in an object: Constant no matter where the object is located.
Weight - a measure of the gravitational force exerted on an object: Weight can change depending on where in the universe it is.
Inertia - the tendency of an object to resist being moved or, if the object is moving, to resist a change in speed or direction.
A. The more massive an object is, the greater the inertia
Physical property - a characteristic of a substance that does not involve a chemical change, such as density, color, hardness,
malleability, ductility, solubility, thermal conductivity and state of matter.
Chemical properties - a property of matter that describes a substance’s ability to participate in chemical reactions such as
flammability and reactivity
Physical Change - a change of matter from one form to another without a change in chemical properties
A. Freezing, melting, cutting, bending, and dissolving.
Chemical change - happens when one or more substances are changed into new substances that have new and different properties.
Composition - is the type of matter that makes up the object and the way that the matter is arranged
A. Physical changes do not change the composition of an object.
B. Chemical changes do change the composition of an object
3 States of Matter - the physical forms of matter, which include solid, liquid, and gas
A. Atoms and Molecules are always in motion
There are 2 kinds of solids
1. Crystalline
a. Occur in a regular repeating pattern of rows
b. Have a distinct melting point
2. Amorphous
a. Particles are not arranged in a regular repeating pattern
b. Gradually melt, no distinct melting point
Viscosity - a liquid’s resistance to flow
Boyle’s Law - the volume of a gas is inversely proportional to the pressure of a gas when temperature is constant. (pressure
increases/volume decreases or pressure decreases/volume increases)
Charles’s Law - the volume of a gas is directly proportional to the temperature of a gas when pressure is constant. (temperature
increases/volume increases or temperature decreases/volume decreases)
Endothermic change - energy is gained by the substance as is changes state
Exothermic change - energy is removed from the substance as it changes state
Evaporation - the change of state from a liquid to a gas that occurs at the surface of a liquid
Boiling - the change of state from a liquid to a gas that takes place throughout the liquid: Boiling point is affected by atmospheric
pressure
Condensation - the change of state from a gas to a liquid
Element – a pure substance that cannot be separated or broken down into simpler substances
Compound – a substance made up of atoms of two or more different elements joined by chemical bonds
1. Cannot be separated by physical means
Mixture – a combination of two or more substances that are not chemically combined
A. Can be separated by physical means
Solution – a single substance composed of particles of two or more substances that are distributed evenly among each other
A. Solute – the substance that is dissolved
B. Solvent – the substance in which the solute is dissolved
Concentration – the amount of a particular substance in a given quantity of a mixture, solution, or ore
Suspension – a mixture in which particles of a material are dispersed throughout a liquid or gas but are large enough that they settle
out
Colloid – a mixture consisting of tiny particles that are intermediate in size between those in solutions and those in suspensions
Speed - the distance traveled divided by the time interval during which the motion occurred.
Average speed
total distance
= -------------------total time
Average acceleration
=
final velocity - starting velocity
----------------------------------------time it takes to change velocity
Velocity - the speed of an object in a given direction
Acceleration - the rate at which velocity changes over time
Force - a push or pull exerted on an object in order to change the motion of the object
Newton (N) - the SI unit for force
Net Force - the combination of all the forces acting on an object
A. Net forces acting in the same direction are added together




25N +
20N =
45N
B. When forces are in opposite directions, subtract the smaller force from the larger force




20N +
25N =
5N
Friction - a force that opposes motion between two surfaces that are in contact
A. The amount of friction between two surfaces depends on two factors:
1. The amount of force pushing the two surfaces together
2. The roughness of the surfaces
Gravity - the force of attraction between objects that is due to their mass
A. The size of gravitational force depends on two things: mass and distance
Law of Universal Gravitation - all objects in the universe attract each other through gravitational force.
Objects fall to the ground at the same rate because the acceleration due to gravity is the same for all objects.
Acceleration - the rate at which velocity changes
Terminal Velocity - the constant velocity of a falling object when the force of air resistance is equal in magnitude and opposite in
direction to the force of gravity.
Newton’s First Law of Motion - an object at rest remains at rest, and an object in motion remains in motion at constant speed and in
a straight line unless acted on by an unbalance force.
Inertia - the tendency of an object to resist any change in motion
A. The larger the mass of an object, the larger the inertia
Newton’s Second Law -
F=ma
Force = mass × acceleration
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
Momentum p=mv
(P) momentum = mass  velocity
(measurement for answer kg · m/s )
A. The more momentum an object has, the harder it is to stop the object or change its direction
The Law of Conservation of Momentum - any time objects collide, the total amount of momentum stays the same
Pressure - the amount of force exerted per unit area of a surface
p=fa
Atmospheric pressure - the pressure caused by the weight of the atmosphere
A. if you go above sea level, atmospheric pressure goes down as you go higher
B. if you go below sea level, atmospheric pressure increases as you go lower
Fluid - any material that can flow and that takes the shape of its container.
A. Particles in fluids move EASILY past each other
B. Includes liquids and gases (ex. air and water)
C. Fluids flow from areas of high pressure to areas of low pressure
Archimedes’ principle - states that the buoyant force on an object in a fluid is an upward force equal to the weight of the volume of
fluid that the object displaces
Bernoulli’s principle - states that the pressure in a fluid decreases as the fluid’s velocity increases
A. This principle is used in flight.
Pascal’s principle - states that a change in pressure at any point in an enclosed fluid will be transmitted equally to all parts of that
fluid.
A. Hydraulic devices use Pascal’s principle to move or lift objects.
Work – the transfer of energy to an object by using a force that causes the object to move in the direction of the force
W=F×d
Work = Force × distance
(answer given in joules)
Power – the rate at which work is done or energy transferred
P=W÷t
Power = Work ÷ time
(answer given in watts)
Machine – a device that helps do work by either overcoming a force or changing the direction of the applied force
A. Work input – the work done on a machine
B. Work output – the work done by a machine
Mechanical advantage – a number that tells you how many times a machine multiplies force.
output force
Mechanical advantage (MA) = ----------------input force
Mechanical Efficiency – a quantity, usually expressed as a percentage, that measures the ratio of work output to work input
work output
Mechanical efficiency = ------------------ × 100
work input
Some work input is used to overcome friction, so work output is always less than work input
There are six types of simple machines
1. Lever – a simple machine that has a bar that pivots at a fixed point, called a fulcrum
2. Pulley – a simple machine that consists of a wheel over which a rope, chain or wire passes
3. Wheel and axle – a simple machine consisting of two circular objects of different sizes: the wheel is larger than the axle
4. Inclined plane – a simple machine that is a straight, slanted surface (also called a ramp)
A. You use less force by spreading the force over a longer distance
5. Wedge – a simple machine that is made up of two inclined planes that move
6. Screw – a simple machine that consists of an inclined plane wrapped around a cylinder
Energy – the ability to do work
Kinetic energy – the energy of an object that is due to the object’s motion
mv²
Kinetic energy = ------2
mass × velocity²
--------------------2
Potential energy – the energy that an object has because of the position, shape, or condition of the object
Energy conversion – a change from one form of energy to another
1. During all energy conversions, some energy is always converted to thermal energy
Law of conservation of energy – states that energy cannot be created or destroyed but can be changed from one form to another
Nonrenewable resources – a resource that forms at a rate that is much slower than the rate at which it is consumed
nuclear energy)
(fossil fuels,
Renewable resources – a natural resource that can be replaced at the same rate at which the resource is consumed
geothermal, hydroelectric, wind, biomass)
(solar,
Atom – the smallest particle into which an element can be divided and still be the same substance.
Nucleus - the center of the atom which is composed of two types of particles
A. Protons – positively charged particles in the nucleus
B. Neutrons – particles of the nucleus that have no charge
Electrons – negatively charge particles found around the nucleus in electron clouds
Ion – if the charges are not equal between protons and electrons, you have a charge particle
Atomic number – the number of protons in the nucleus of an atom
Isotope – atoms that have the same number of protons but have different number numbers of neutrons
Radioactive – an isotope that is an atom with a nucleus that will change over time (very unstable)
A. They spontaneously fall apart over time
B. They give off particles and energy
Atomic mass – the weighted average of the masses of natural isotopes of an element
Dmitri Mendeleev - arranged elements in order of atomic mass they had similar properties that occurred in a
Periodic - describes something that occurs or repeats at regular intervals
repeating pattern.
Periodic law - states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of
the elements
Metals - most elements are metals
A. most found to the left of the zigzag line
B. Properties: shiny, malleable, ductile, good conductors of thermal energy and electricity
Nonmetals
A. found to the right of the zigzag line
B. Properties: dull, not malleable, not ductile, poor conductors or thermal energy or electricity
Metalloids - also called semiconductors
A. border the zigzag line
B. they have some properties of metals and some of nonmetals
Period - a horizontal row of elements in the periodic table
1. Most reactive elements on far left (alkali metals)
2. Least reactive elements on the far right (noble gases)
Group - a vertical column of elements in the periodic table
1. Elements in a group share chemical properties
Medium - a substance through which a wave can travel; can be solid, a liquid, or a gas
Mechanical waves - waves that need a medium to travel through
Electromagnetic waves - waves that transfer energy without going through a medium
Transverse wave - a wave in which the particles of the medium move perpendicularly to the direction the wave is traveling.
A. Crest - the highest point of a transverse wave
B. Trough - the lowest point between each crest
Longitudinal wave - a wave in which the particles of the medium vibrate parallel to the direction of the wave motion
A. Compression - a part of a longitudinal wave where the particles are crowded together
B. Rarefaction - a part of a longitudinal wave where the particles are spread apart
Amplitude - the maximum distance that the particles of a wave’s medium vibrate from their rest position
Wavelength - the distance from any point on a wave to an identical point on the next wave
Frequency - the number of waves produced in a given amount of time
Reflection - when a wave bounces back after hitting a barrier
Refraction - the bending of a wave as the wave passes from one medium to another at an angle
Diffraction - the bending of waves around a barrier or through an opening