motion the base si units for length, time, and mass are meters, seconds, and kilograms movement in...
TRANSCRIPT
MotionThe base SI units for length, time, and mass are
meters, seconds, and kilogramsMovement in relation to a frame of reference is
called relative velocityVectors (like velocity) have both magnitude and
direction; scalars (like speed) only have magnitude
The slope of a Distance versus Time graph tells us the average speed
Velocity is calculated by dividing displacement by time
MotionAcceleration is the rate at which velocity
changesObjects that are accelerating have parabolic
Distance versus Time graphsAdding vectors together results in another
vectorChanging direction or speed will be the result
of acceleration
ForcesMass is a measurement of inertiaStatic friction is the friction when an object
hasn’t started to move yetIf the net force is zero, an object’s velocity
will not changeF = map = mv
ForcesMomentum is conserved if there are no net forces
acting on a systemImpulse is the change in momentum, and is the
product of force and timeThe electromagnetic force is the only one that
can both attract and repelThe strong nuclear force holds together protons
and neutronsThe gravitational force is the weakest of the
fundamental forces, but is the most easily observed when dealing with large objects
ForcesNewton’s Law of Universal Gravitation states
that all mass is attracted to all other massAction-reaction forces do not cancel out
because they act on different objectsForces can be acting on objects that are
either moving or not movingForces do work when they are applied in the
direction of motion
Work & EnergyPower is the rate of doing workMachines output less work than is put into
them because friction makes their efficiency less than 100%
Actual Mechanical Advantage < Ideal Mechanical Advantage
Machines change the size of force, the direction of force, and/or the distance of force
Work & EnergyWork transfers energyMechanical energy is potential + kineticEnergy is conservedFriction turns kinetic energy into thermal
energyE = mc2
Fossil fuels (coal, oil, natural gas) represent the majority of energy resources in use
Energy gets changed from one form to another
WavesWaves transfer energyTransverse waves are perpendicular & longitudinal
waves are parallel to propagation; surface waves are both
v = fλDiffraction is when a wave bends around an obstacle;
the longer the wavelength, the more it bendsWave amplitude determines energyThe Doppler Effect explains why there is an apparent
change in frequency when there is relative motion between a wave source and an observer
WavesRefraction involves the change in direction of
a wave because of a change in speedElectromagnetic waves can travel through
empty space (a vacuum)Mechanical waves require a medium in which
to travelWaves can interfere, matter cannot
LightPolarized waves only oscillate in one
directionRadio waves have low frequency and long
wavelength, low energy and penetrate lessGamma rays have high frequency and short
wavelength, more energy and penetrate moreThe Photoelectric Effect is when electrons
are emitted from a metal when high frequency light hits it
LightMirages are caused by total internal
reflectionLight is both a particle and a waveThomas Young’s double-slit experiment
showed light interfering and acting wavelikeAll electromagnetic waves have the same
speed for a given medium
ElectricityElectric charge can be positive or negativeThe SI unit for charge is CoulombsOpposite charges attract, likes repelElectric force depends directly on the size of
the charges and inversely with the square of the distance
Charge is conservedObjects can be charged by friction, induction,
and conduction
ElectricityResistance depends directly on temperature
and length, and inversely with widthV = IRCurrent is measured in AmpsIn parallel circuits, each element functions
independentlyP = IVGrounding, fuses, and circuit breakers are
common electrical safety devices
ElectricityIn series circuits, either everything works or
nothing worksMetals and other conductors have electrons
that are free to move; plastic and other insulators do not
Electric fields lines point away from positive charges and towards negative charges
The electric force is responsible for contact forces like friction and the normal force
MagnetsMagnetic fields are strongest near the polesMagnets always have both a north and a
south poleMagnetic materials are magnetized when
their magnetic domains are alignedMagnetism is ultimately caused by moving
chargesA solenoid is a stack of loops of wireFaraday’s Law relates changing magnetic
flux to induced currents
MagnetismMotors convert potential energy (chemical,
electric, etc.) into mechanical energyMoving charges are deflected perpendicular to
magnetic fields and their velocitiesTransformers change AC voltages via
inductanceThe earth’s magnetic field is caused by
convection currents in its mantleThe strength of an electromagnet is directly
proportional to the number of coils and current