SI UnitsUnits used by all scientist to measure observations
● Length = meter (m)● Mass = gram (g)● Force = Newton (N)● Speed = m/s● Time- seconds (s)● Acceleration = m/s2
● Work, KE & PE = Jules (J)● Power = Watts (W)
Units are very important….they tell us what we are measuring!!
NASA’s Metric Disaster
What is a Vector
A vector is a quantity that includes direction as well as magnitude
Displacement- 10 m, west
Velocity- 10 m/s, west
Acceleration- 10 m/s2, west
Force- 10 N, down
Speed
The speed of something is the rate at which it covers distance
Speed = Distance/Time
Units!Distance = meters (m)Time = seconds (s)Speed = m/s
Speed Time
Distance
Velocity
Same as speed, but now has a direction
Because velocity has a magnitude (speed) and a direction it's a Vector
Velocity = Distance/Time + Direction
AccelerationThe change of velocity over time
Since velocity consists of speed and direction, you can accelerate by:
● Speeding Up● Slowing Down ● Changing Direction
Acceleration is also a vector
Units: m/s2
Acceleration Due to GravityAcceleration due to gravity
g = 9.8 m/s2
The higher the drop, the faster the Velocity
Unlike other accelerations- this is a constant
Mass vs Weight
Mass is how much matter your body is composed of. This does not change based on location
Weight has to do with the pull of gravity. Since gravity can change, your weight can change. Ex: you weigh less on the moon.
Newton’s First Law of Motion
An object at rest will stay at rest and an object in motion will stay in motion, unless an unbalanced force acts upon it
Balanced Force: Net force = 0 N Object is at rest or moving at a constant speed
Unbalance Force: Net Force is greater than 0 N and is accelerating
Newton's 2nd Law of Motion
Force causes objects to accelerate- How much they accelerate is based on how much force is applied divided by its mass. Force = mass x acceleration
Units Force = N Mass = KgAcceleration = m/s2
F
M A
Net ForceCombination of forces on an object
To find the Net Force, add or subtract the magnitudes
If arrows are going in the same direction you ADD
If arrows going in opposite direction you SUBTRACT
5N 8 N
5 N
6 N
20N
Net Force = 10 N, left
Newton’s Third LawFor every action (force), there is an equal and opposite reaction (force).
What is Work?The change a force causes when it acts upon something.
How far did the object move when you applied force to it?
Work = Net Force x Distance
SI Unit: Joule ( Newton ● meter )
If nothing moves, then no work is done, no matter how great the force
Kinetic EnergyEnergy of a moving object
Every moving object has the capacity to do work- by striking something else, the moving object can exert a force and cause the second object to shift its position (energy causes change)
● Depends on mass and speed - uses Joules (J) for unit● The greater the mass and speed, the greater the KE
KE = ½ mass x velocity2 or KE = ½ mv2
Potential EnergyEnergy of Position - a resting object has the potential to apply work to a surface if dropped
Gravitational Potential Energy
PE = mass x acceleration due to gravity x height
PE = mgh
If you are given the object's weight in Newtons, you do not need to multiply mass and acceleration. Remember, mass x acceleration = Force = N
Conservation of EnergyEnergy cannot be created or destroyed, although it can be changed from one form to another.
What this means is that the total amount of energy in a system isolated from the rest of the universe remains constant, even though energy may transform from to form to another within the system
Energy before = Energy after
Climate Change
Climate is the aggregated pattern of weather
Climate change means altered patterns.
Small temperature changes big changes in the patterns
CausesIncreased concentration of CO2 (right)
Burning fossil fuels in cars, industry and homes
Deforestation
Burning of forests
Greenhouse Effect
1. Radiant energy from the sun hits Earth
2. Gases trap heat instead of it escaping into space
3. Ice bounces heat back into space: less ice, more absorption of heat by land and water
Causes Global Warming
Other Greenhouse Gases
CFCs and HCFCs- artificially made gases for refrigerators and air conditioners. Lifespan of about 100 years.
Methane- 21x more efficient than CO2, from wetlands, production of fossil fuel, decay of organic matter, rice growing, digestion by product of livestockLifespan of about a dozen years
Nitrous oxide- 310x more efficient than CO2, with a lifespan of about 120 years. Given off when fossil fuels and organic matter are burned, when fertilizers are used, and some industrial processes.
Heat TransferHeat is transferred (moves) in one direction: from a warmer object to a cooler object
Transferred in one of three ways:
1. Conduction2. Convection 3. Radiation
Conduction, Convection and RadiationConduction- heat is transferred from one particle to the next particle without the particles moving or changing place
Ex: metal spoon gets hot when sitting in a pot of hot water
Convection: movement that transforms heat by movement of currents within the particles. The particles are moving and thereby transferring heat.
Ex: a pot of water starts to boil- current of hot water at the bottom moving to the top
Radiation: transfer of energy by electromagnetic wavesEx: Sun’s rays heating earth
Changes in States of Matter
Adding or removing heat causes objects to change their state of matter
Plasma
DensityThe density of a material is its mass per unit volume Density of water: 1 g/ml
Density of WaterBuoyant Force: An object in fluid is acted upon by an upward force that arises because pressure in a fluid increases with depth
Density of water = 1 g/ml
If an object has a density less than 1, it will float. If it has a density greaterthan 1, it will sink
Electric ChargeFundamental property of certain elementary particles of which all matter is composed
2 Types
1. Positive (proton)2. Negative (electron)
Charges of the same sign repelCharges of the opposite sign attract
Due to the electric field created by particles
Electric CurrentFlow of electrons from one area to another
Unit: Ampre (Amp) (A)
Potential Difference (Electric Potential) Voltage
● As electrons gather on one side, they want to flow to side with less potential● Volt- unit to measure difference of potential● Voltage- causes current to flow through circuit (the energy that moves current)
○ Circuit- complete conducting path
Like Potential Energy!
Magnetic EarthEarth’s core is made of Iron
Earth’s magnetic north is not the same as the North Pole
● About 1250 km (776 mi) away
Compass uses the Earth’s Magnetic field…...so do animals!
Earth’s Magnetic Field deflects solar wind, which would strip the ozone layer and expose us to UV radiation!
Magnetic Field and Electric ChargeEvery electric current has a magnetic field around it
Right Hand Rule
WavesWaves carry energy from one place to another by a series of periodic motion
● Mechanical Waves: travel only through matter Ex: ocean waves, sound
● Electromagnetic Waves: varying electric and magnetic fields can travel through vacuum (no matter) Ex: sunlight
Properties of Transverse WavesParticles move perpendicular to the direction of the wave
Amplitude: height away from rest position
Wavelength: the distance between two corresponding parts of a wave
Properties of Longitudinal WavesWaves
Particles move parallel to the wave
Amplitude: Height above resting position (middle)
Wavelength: the distance between two corresponding parts (compression to compression)
Light
● the natural agent that stimulates sight and makes things visible● It is both a particle and a wave
Refraction: change in direction of light waves as they enter a region (water)
Reflection: light wave strikes an obstacle and rebounds from it- enters eye
Electromagnetic Spectrum
All the radiation from the sun is found on the Electromagnetic Spectrum
Prisms and RainbowsWhite Light: combination of all the colors on the spectrum
Prism: separates white light into component colors
Rainbow: light shining through tiny droplets of water, each droplet acting like a prism
Why do you see a certain color?The color you see is the wavelength of the color being reflected. All other colors are absorbed by the object.
Structure of an AtomAn atom is the smallest particle that makes up all matter.
Composed of 3 main particles
1) Proton- inside the nucleus, + charge2) Neutron- inside the nucleus, no charge3) Electron- orbit the nucleus, - charge4) Nucleus- The center of an atom. Where
Proton and Neutron are found-
Evolution of the Atom
Atomic Number Element: a substance consisting of
atoms with same number of protons.
Ex: Hydrogen: all Hydrogen atoms have 1 proton
Atomic number- the number of protons an atom has. Found on the Periodic Table
Atomic Mass
The atomic mass is how the much the atom's weigh -Average!
Atomic mass = the number of protons and neutrons in the atom.
Protons and Neutrons weigh about the same. Electrons are so small, their mass is negligible
Electron ShellsWe use electron shells to model how electrons move around the nucleus.
Electron Cloud: electrons move in shells, but we can't know where they are at any one time, so we say they create a cloud around the nucleus
How to draw atom using the Bohr Model
Oxygen’s atomic number is 8 and its atomic mass is 16. It is also considered neutral. That means:
There are 8 protons and 8 neutrons in the nucleus.
2 electrons are in the first shell and 6 electrons are in the second shell
Valence ElectronsValence Electrons are the electrons on the outermost shell
These electrons are important
because they determine how
atoms will interact with other
atoms.
IsotopesIsotopes are atoms that have a different amount of protons and neutrons
Can be determined by the Mass Number = P + N 146C
Isotope Notation
1125Na
6431Ga
How many protons and neutrons?
Periods and Groups
Group: Columns of the Periodic Table 18 in total Contain Families Increasing Valence Electrons (colored columns only)
Period: Rows of the Periodic Table 7 in total Increase by electron shells
Metals, Semimetals (Metalloids) and Nonmetals
Families
Goups that have similar properties
Alkali Metals- highly reactive& have 1 valence electron
Alkaline Earth Metals- reactiveTransition Metals- crazyHalogens-highly reactiveNoble Gases- Unreactive
