69 terms

dynamics

the study of motion and of physical concepts such as force and mass

kinematics

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

displacement

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

acceleration

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

inertia

the tendency of an object to continue in its original state of motion

mass

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

newton

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

friction

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

joule

(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

gravity,

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

work

transfers energy to a system by displacing it with an applied force

heat

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

watt

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

impulse

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

radian

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