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AP Physics Exam
Stack #194887
Question | Answer |
---|---|
Physics | the study of matter and energy and the relationships b/w the two |
Mechanics | motion of objects |
Mechanics: statics | objects at rest; balanced forces |
Mechanics: Dynamics | objects in motion; balanced or unbalanced forces |
Galileo | 1564-1642 studied velocity and a |
thermodynamics | heat, temp, and behavior or a large number of particles Joule- work can be changed into heat |
electromagnetism | waves, e and m |
Oerstad | found relationship between E and M (compass needle deflected by current carrying wire) |
Faraday and Henry | operate a current in a wire by a changing M field |
optics | study of light's behavior and interactions w/ materials |
Maxwell | amazing laws of Maxwell |
Einstein: general relativity | mass alters the space around it |
Einstein: special relativity | describes motion of objects near the speed of light c same for all observers in an intertial frame of reference the faster you move near the speed of light, the slower the time objects increase in mass near the speed of light |
quantam mechanics | particles at atoms/subatomic level (57...80? particles) connects behavior or matter at submicroscopic level to macroscopic observations |
Laws and Principles | tell how objects act; does not limit behavior |
Theory | reasonable explanation for a series of events tells why material acts as it does ex: gravity, light, relativity, evolution |
fundamental unit for electric current | A |
intensity of light fund. unit | cd |
amount of substance fund. unit | mole |
personal error | mistakes made by experimenter; illegitimate |
systematic error | flaw in experiment or apparatus |
random errors | can't be totally eliminated; follow Gauss distribution function |
Distrubution Law | 68.3/95.5/99.73 |
standard error | sigma/square root of N error of the mean |
weight scalar? | no vector (5 N down) (mass is scalar) |
properties of vectors | equality (if parallel), addition, commutative, associative, negative, subtraction, multiplication by scalar |
dot product | vector(vector)= scalar= AB costheta |
cross product | vectorxvector=vector=ABsintheta |
unit vectors | dimensionless vectors 1 unit in length used to specify a given direction |
vectors act ____ of one another | independently |
mechanics: kinematics | study of motion; kinematic eqs. |
mechanics: dynamics | study of motion and the forces that cause the motion |
terminal v | the velocity reached when the force of air resistance equals thew weight of the object |
hyperbola | y=k/x |
area under v v. t curve | displacement |
gravitational mass | platform balance or spring balance |
inertial mass | inertial balance |
vx= | vcostheta |
vy= | vsintheta |
max height= | .5vo^2sin^2theta/g (g is +) |
horizontal range= | vo^ssin2theta/g (g is +) |
uniform circular motion | particle/object traveling in a circular path at a constant speed |
why does ac point towards center of circle? | change in vs pt. toward circle's center |
curvilinear motion | speed and direction are changing |
throw ball upward in moving vehicle | stationary observer sees parabolic path |
relative v and a | s and s' (page 21) |
acceleration of a particle measured by an observer in the earth's frame of reference is the same as the | acceleration measured by any other observer (moving w/ a constant speed) |
classical mechanics | relationship b/w motion and the forces that cause the motion; obj. that are large compared w/ atoms traveling at speeds much less than c |
classic mechanics kinematics | w/o forces |
classic mechanics dynamics | w/ forces |
force | physical quantity that can affect the motion of an object (vector) |
Issac Newton- F may cause | acceleration |
balanced forces | net force=o |
unit for forces | MKS- N CGS- dyne British- pund |
contact forces | physical contact |
field forces | gravity, e, and m |
First Law of Motion; LAw of inertia | an object in motion will continue in motion and an object at rest will remain at rest unless acted upon by an unbalanced force |
inertia | resistance to a change in motion; mass |
mass | measure of inertia |
weight | force of g acting on an object; varies w/ location |
2nd law of motion | f=ma; the direction of the a will be in the direction of the unbalaanced force |
3rd law of motion | law of action and reaction: every force is accompanied by an equal but opposite force |
n | force pressing 2 surfaces together |
friction is a _________ force | electromagnetic due to temporary attraction of contact points (needed to walk and drive) |
static friction | max. frictional force b/w 2 obj. at rest and on the verge of slipping |
when an obj. is sliding down at incline at constant speed muk= | tan(critical angle) |
centripetal force | unbalanced force; force that keeps obj. or particle moving in uniform circular motion; constant or uniform speed but change in direction |
satellite motion | weight of satellite provides Fc so v= square root(Gm/r) m=mass of earth and G=6.67x1o^-11 |
Considering a ball on a rotating spring at angletheta from rest position (28) T at bottom = and at= | at=gsin(theta) and at bottom T=Fc+mg |
classes of forces | gravitational, electromagnetic, strong nuclear, weak nuclear |
gravitational force | force of attraction b/w all masses (earth exerts force on moon to keep it in orbit while moon's force on earth causes tides) weakest of all 4 forces |
electromagnetic force | force b/w charged particles- friction, electric forces, and m forces |
strong nuclear force | force of attraction holding protons and neutrons together in the nuclear |
weak nuclear force | force within the particles inside the nuclear |
proton quarks | 2 up 1 down |
neutron quarks | 2 down 1 up |
GUT (grand unification theory) | one theory that would explain all forces *having prob. w/ gravitational force |
electroweak | combines 2 and 4 |
up top charm | +2/3 |
down bottom charge | -1/3 |
(super)string theory | all matter is a vibrating string of energy |
sliding friction | resistive force an object moving along a rough solid surface; nearly independent of v; may assume constant in magnitude |
friction force depends on v for | objects fallings through liquid at low speeds or small particles of dust falling through air |
friction force depends on v^2 for | large objects falling through air at high speeds |
resistive force | direction is opposite motion of the object; increases w/ increased speed |
b depends on | medium, shape, and dimensions of the object |
b is proportional to ____ | r for spheres |
tao= | m/b or time constant (time it takes for obj. to reach 63 percent of its terminal velocity) |
c | drag coefficient (.5 for spherical obj. but up to 2 for irregulary shaped obj.) |
inertial frame of reference | one in which Newton's laws hold true; frame is at rest or moving w/ a constant v |
non-inertial frame of reference | frame itself is accelerating and Newton's laws don't apply (review 32) |
non inertial frame v. intertial frame when passenger slides towards door | passengers invents fictitous force that pushes outward; friction provides Fc and if it's not enough person slides toward door in a straight line path |
E | capacity to do work |
work | force exerted through a distance done by a constant definted as the product of the component of force in the direction of movement and the magnitude of the displacement (scalar) |
units for work | (j or Nm), erg (dynecm), ftlb |
dot product | product of the magnitude of A and the projection of B onto A |
dot product properities | commutative, distrubutive,if a and b are antiparallel- -AB if parallel is AB |
area under F v. x | work done |
k | spring constant; stiffness of spring |
force in hooke's law | restoring force; restores original conditions |
block on spring oscillating to far right | x=max; v=o; a=-max and f is toward center |
block on spring oscillating to far left | x=-max; v=o, a=max, F=+ (towards center) |
work done by the applied force on a spring | is equal and opposite the work done by the spring Ws |
Work Energy Thm. | W=deltaK (true for constant or varying force) W=change in Kr (for rotational motion) |
power | rate at which W is done; time rate of E transfer; work per unit time |
watt | J/s |
Pt unit | kWhr |
U | stored E that can be changed into K or work (work done equals the decrease in potential E); energy of position, stored E, mgh (where change in h is hi-hf) |
conservative forces ex. | gravitational, elastics (spring), electrostatic |
dissipative forces | nonconservative; reduces an object's ability to do work |
law of cons. of mech. E | sum of K and U Es of an ideal system remains constant |
ideal | only conservative forces, no friction |
graph for springs | pg. 40 |
linear momentum | vector in direction of velocity Ns or kgm/s |
impulse momentum thm | I=change in p (newtons 2nd law) |
law of conservation of momentum (newtons 3rd law) | total momentum of an isolated system remains constant |
isolated system | no external forces |
xcm= | 1/M(the integral of xdm) |
M= | integral of dm |
the cm moves like an imaginary particle of mass M under the influence of the | resultant external force on the system |
if an object explodes due to an internal force | cm of mass still follows parabolic path |
the center of mass of a system remains at rest unless | acted upon by an external force |
rotary motion | motion of an obj. about an internal axis, can't be treated as a particle |
axis | straight line about which the rotation takes place |
circular motion | motion of a particle along a circular path |
rigid body | nondeformable (for ball and floor) separations b/w all pairs of particles in the body remains constant |
pure rotational motion | rotation of a rigid body about a fixed axis |
first law (in terms of chp. 10) | an obj. rotating about an axis tends to continue to rotate unless acted upon by an unbalanced torque |
rotational intertia | scalar units kgm^2 |
rotational inertia | resistance to a change in rotary motion depends on the mass, the distribution of the mass, and the axis of rotation |
moment of inertia I= integral of | r^2dm |
parallel axis thm. | the rotational inertia of a body about any axis is equal to the rotational inertia (MD^2)it would have about that axis if all its mass were concentrated at its cm plus its rotational inertia about a parllel axis through its cm |
torque | applied torque (unbalanced torque) causes rotation |
consider a particle rotating due to Ft torque= | I(alpha) |
rolling motion | rotates and translates |
consider the motion of a homgeneous rigid body w/ a high degree of symmetry rotating about a moving axis graph called and abs. mins called | cycloid; cusp |
rolling motion | combination of pure rotational and pure translational motion (wheel graphs on 55) |
units of L | kgm^2/s |
for cross porudcts Absintheta= | abs. value of C |
cross product properties | not commutative, AxB (if parallel)=0 but (if perp.)=AB, distributive, chain rule |
L of particle in circular motion= | mvr |
L of a rigid body about a fixed axis= | I(omega) |
conservation of L | The L of a system remains constant unless an external torque acts upon it |
precession | change in the direction of vertical axis (ex: earth); the weight of the obj. provides a torque which causes the change in direction |
eq. static v. dynamic | at rest v. at constant speed; p and L are constant |
elasticity | ability of a solid to reutrn to its orgiinal shape when external forces are removed |
assumed obj. aren't deformed | but they are; molecular explanation |
stress | F/A units- N/mm or Pa |
strain | relative amount of deformation |
compressibility | reciprocal of bluks modulus |