Praxix 5159 Physical Sciences

Speed

How fast an object is moving (m/s)

Velocity

the speed of an object in a given direction. (ex: a car an a wagon on a train have different velocities)

Acceleration

the rate at which the velocity of an object changes over time. ____ of an object changes if it's speed and/or direction change (velocity/time)

Momentum

how strong a moving thing is (why you can't bowl with a ping pong ball)

Friction

resistance of motion when one object rubs against another. Anytime 2 objects rub against one another, they cause this. Starts to slow down ---> converts from kinetic to heat energy

Work

the transfer of energy. Product of force and distance (__ = fx). Unit is a joule

Energy

transferred through action of work.

Power

the rate at which work is done.. how fast work is done. ____ = work completed/time required

Gravitational Attraction

the force that draws two objects together. It is governed by the law of universal gravitation, which states that the force of attraction between two objects is related to the mass of the objects and inversely related to the distance between the two. (ex: if the mass of one object doubles, then the grav. Attraction between them doubles)

Mass

the amount of matter that an object contains and is a measure of its inertia (grams of kg)

Weight

a measure of gravity's pull on an object (newtons)

Newton's First Law

inertia - An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. (need for seatbelt is due to inertia)

Newton's Second Law

the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object. If you apply more force to an object, it will accelerate at a higher rate(M= F/A)

Newton's Third Law

"for every action there is an equal and opposite reaction" Forces acting in pairs (ex: when 2 skaters push against each other with an equal and opposite force, sitting in a chair- the force of your body pushes down on the chair, which counterbalances that force by pushing up on your body with equal but opposite force)

Inclined Plains

a slanting surface that connects a lower level to a higher level

Projectile Motion

the motion of an object that is dropped, shot, thrown, launched, or otherwise thrust into the air (multiple directions)

Periodic Motion

any motion that is repeated in equal time intervals, or a motion that repeats itself in equal regular periods or intervals. (ex: clock pendulum)

Law of Conservation of momentum

the total amount of momentum in a system cannot change. (ex: the firing of a cannon. Cannon is much bigger than the ball it discharges, but the law of conservation of momentum says that no momentum is lost. So during the firing of the cannon, the ball shoots out the front and the cannon moves backward - newton's 3rd law)

Buoyancy

Things that are made of stuff that sink float if they're shaped right. Objects displace water the weight of that object to float. Archimedes

Electric Charges

law states that like charges repel and unlike charges attract

Conductivity

the measure of the ease at which an electric charge or heat can pass through a material. A conductor is a material which gives very little resistance to the flow of an electric current or thermal energy. Materials are classified as metals, semiconductors, and insulators. Metals are the most ____ and insulators (ceramics, wood, plastics) the least ___

Conductors

Made of materials that electricity can flow through easily. Materials are made up of atoms whose electrons can move away freely (copper, aluminum, gold, silver)

Insulators

Opposite of conductors. Atoms not easily freed and are stable, preventing or blocking the flow of electricity (glass, porcelain, plastic, rubber)

DC Current

charges always flow in the same direction: positive to negative (batteries)

AC Current

charges continually "alternate" or reverse directions (power that comes from a power plant)

Voltage

the electric force that causes the free electrons to move from one atom to another.

Ohm's Law

states that the current passing through a conductor is proportional to the voltage over the resistance. (I= V/R I is current in amps, v voltage, R resistance)

Nature of Light

Aborsb light and change into heat and reflect color. Black absorb all colors of light and convert to heat White absorbs all colors and reflects very little

Visible spectrum and color

Most colors humans see are from reflected light. Color of an object that is seen isn't contained within that substance, but the color is merely reflected from that object and perceived by a human as that. While = reflect all colors. Black = absorb all colors

Ultraviolet

light with higher frequency (lower wavelength) than visible light. Prolonged exposure to UV light causes sunburn and can cause skin cancer. The earth's ozone layer absorbs most of the incoming UV light from the sun.

Infrared

light with lower frequency (higher wavelength) than visible. is emitted from all objects at or near room temperature in the form of blackbody radiation.

Microwave

Excitations cause many molecules such as water to oscillate and heat up, which is how microwave ovens work.

Amplitude

the maximum distance of oscillation from the resting point, midpoint, or equilibrium level of a wave to its peak or trough. Measure of wave strength, larger ____→ greater wave strength (tall)

Frequency

measure of how often a wave oscillates at any given point. Number of waves in a given unit of time. Calculated by dividing # of waves by the time (measured in Hertz)

Wavelength

the distance between neighboring crests or troughs

Reflection.

wave bounces back after hitting an object (echo)

Refraction

bending of a wave as the wave passes through one medium into another medium (spoon placed in d glass of water)

Diffraction

bending of waves through an opening or around a barrier (refraction of light through prism)

Absorption

occurs when a wave decreases as it passes through an object

Inference

When waves overlap. Two types of inference: constructive and destructive

Doppler Effect

Apparent change in the frequency (number of waves) of a wave caused by motion between the source of the wave and observer (ex: when fire truck moves towards you the waves have more frequency so it appears louder) As it gets closer sound waves bunch up and you get it at a higher frequency

Mirrors

classified by their shape: plane, concave, or complex

Atomic number

number of protons in nucleus

Atomic mass

number on bottom of element

Covalent Bonding

bond formed by atoms sharing electrons

Ionic Bonding

bond formed by the transfer of electrons from one atom to another.

6.02 x 1023 atoms

1 mole

Percent Composition:

the percent of the total mass of the compound that is due to that component. Mass due to specific component / total molar mass of compound x 100(1. Add masses of both , use mass of element as numerator and total as denominator)

Combustion

characterized when a reactant combines with oxygen to form an oxide product (x + O2 -→ XO)

Oxidation

loss of electrons

Single replacement

occur when a single, more reactive element displaces another element in an existing compound (X+ YZ → Y + XZ)

Double Replacement

occurs when the cations of 2 ionic compounds displace each other (XY + AB -→ XB + AY)

Endothermic Reactions

new absorption of energy (cold packs used for injuries absorb heat, so they feel cool when activated/ evaporation)

Exothermic Reactions

chemical reactions that result in a net release of energy (ex: burning of gasoline in a vehicle, condensation)

Acids

increase # hydrogen ions. Taste sour and can change colors. Turns blue litmus paper red (Ph 1-6)

Bases

Increase # of hydroxide ions. Tastes bitter, feels slippery, and can change colors. Turns litmus paper blue (Ph 8-14)

7

Neutral pH

Neutralization

Occurs When a strong acid and a strong base solution are mixed, and the products do not have characteristics of either acids or bases. Instead, a neutral salt and water are formed

Buffers

Solutions that resist any change in pH when acids or bases are added to the solution (work because the weak acid reacts with a strong base to form a weaker base and water)

Increase

For solids, Increase in temperature = _______ in solubility

Increase

For gasses, Increase in temperature = ____ in solubility