69 terms

AP physics vocab


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the study of motion and of physical concepts such as force and mass
the part of dynamics that describes motion without regard to its causes
geocentric model
Model of the Solar System with the Earth in the center. First created by the Greeks.
heliocentric model
earth and the other planets revolve in circular orbits around the Sun
frame of reference
a choice of coordinate aces that defines the starting point for measuring any quantity
change in position
average speed
the length of the path it travels divided by the total elapsed time
instantaneous velocity
the limit of the average velocity as the time interval becomes infinitesimally small
instantaneous speed
a scalar quantity defined as the magnitude of the instantaneous velocity
the changing of an object's velocity with time
instantaneous acceleration
the limit of the average acceleration as the time interval goes to zero
motion diagram
a representation of a moving object as successive time intervals, with velocity and acceleration vectors sketched at each position
free-fall acceleration
any object moving freely under the influence of gravity alone, regardless of its initial motion
projectile motion
objects that move in both the x and y directions simultaneously under constant acceleration
field forces
a mass at one location affects themotion of a distant object despite no evident physical connection between the two objects
contact forces
motion that is a result from physical contact between two objects
newtons first law
an object moves with a velocity that is constant in magnitude and direction unless a non-zero net force acts on it
the tendency of an object to continue in its original state of motion
a measure of the objects resistance to changes in its motion due to a force
newton's second law
the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass
the SI unit of force
gravitational force
the mutual force of attraction between any two objects in the universe
Newton's third law
if object 1 and object 2 interact, the force exerted by object 1 on object 2 is equal in magnitude but opposite in direction to the force exerted by object 2 on object 2; forces act in pairs
normal force
an elastic force arising from the cohesion of matter and is electromagnetic in origin
free-body diagram
crucial in applying newton's laws, arrows that represent forces on a diagram
resistance the a moving object encounters as it interacts iwth its surroundings
force of static friction
the force that counteracts an applied force and keeps the can from moving acts to the left
force of kinetic friction
the friction force for an object in motion
impending motion
when an object is on the verge of slipping
coefficient of static friction
the magnitude of the force of static friction between any two surfaces in contact
coefficient of kinetic friction
the magnitude of the force of kinetic friction acting between two surfaces
terminal speed
when the two forces balance each other, the net force is zero, and the acceleration is zero
object in equilibrium
has no net external force acting on it
(NxM) SI unit for work
work-energy theorem
the net work done on an object is equal to the change to the chance in the object's kinetic energy where the change in the kinetic energy is due entirely to the objects change in speed
kinetic energy
object of mass moving with a speed
conservative force
nonconservative force
dissipative, which means that it tends to randomly disperse the energy of bodies on which it acts, heat or sound
potential energy
the work they do can recast as a quantity that depends only on the beginning and end points of a curve, not the path taken
Hooke's law
the force exerted by the spring, must be proportional to the displacement or where k is constant of proportionality the spring constant carrying units of newtons per meter
elastic potential energy
equal to the negative of the negative of work done by the spring
transfers energy to a system by displacing it with an applied force
the procces of transferring energy through microscopic collisions between atoms or molecules.
mechanical waves
transfer energy by creating a disturbance that propagates through air or another medium
electric transmission
transfers energy through electric currents
electromagnetic radiation
transfers energy int eh form of electromagnetic waves such as light, microwaves, and radio waves
conservation of energy
energy is conserved; it can't be created or destroyed, only transferred from one form into another
average power
an external force does work on an object in the time interval
instantaneous power
the component of force in the direction of the average velocity
the SI unit of power
center of mass
the point in the body at which all the mass may be considered to be concentrated
newton's second law and momentum
the change in an object's momentum divided by the elapsed time equals the constant net force acting on the object
continuous application of a force over a period of time
impulse momentum theorem
the impulse of the force acting on an object equal the change in momentum of that object
conservation of momentum
when no net external force acts on a system, the total momentum of the system remains constant in time
elastic collision
both momentum and kinetic energy are conserved
inelastic collision
momentum is conserved but kinetic energy is not
perfectly inelastic collision
momentum is conserved kinetic energy is not, and the two objects stick together after the collision, so their final velocities are the same
unit of angular measure
angular position
the angle measured in radians
angular displacement
the difference in its final and initial angles
average angular acceleration
the change in its angular speed divided by change in time
instantaneous angular acceleration
the limit of the average angular acceleration as the time interval approaches zero
tangential speed
the magnitude of a particle moving in a circular path
tangential acceleration
equals the distance of that point from the axis of rotation multiplied by the angular acceleration
centripetal acceleration
the acceleration vector always points toward the center of the circle
inverse square law
if two particles with masses m1 and m2 are separated by a distance a gravitational force acts along a line joining them
escape speed
large enough speed that it can soar off into space and never return
kelper's laws
all planets move in elliptical orbits with the sun at on focal points; a line drawn from the sun to any planet sweeps out equal areas in equal time intervals; the square of the orbital period of any planet is proportional to the cube of the average distance from the planet to the sun