# Shared Flashcard Set

## Details

Chapter 1-4
first test for physical science
44
Physics
09/25/2011

Term
 science
Definition
 a discipline of focused study that is systematic, comprehensive, and addresses specific questions   -collective findings of humans about nature, and a process of gathering and organizing knowledge about nature
Term
 empiricism
Definition
 data based/driven test explanation based on data
Term
 objectivity
Definition
 ALL the data, not choosing some data and not other -look at the same data data does not depend on the observer
Term
 rational
Definition
 logical connection between data explanation -math
Term
 assumptions science makes about the material world
Definition
 1. nature (material world) understandable 2. nature is uniform (in time and space) data only implies to that place and time 3. observable patterns in nature provide clues to understand unobservable patterns
Term
 Aristotle's ideas on Motion
Definition
 2 types 1. natural motion: moves on its own/moves with nature. i.e. rock falls down)   2. forced motion: throw rock up   everything composed to 4 elements: fire, air, water, earth
Term
 speed
Definition
 the distance traveled per time   speed= distance covered/travel time
Term
 velocity
Definition
 the speed of an object and specification of it direction of motion
Term
 acceleration
Definition
 the rate at which velocity changes with time; the change in velocity may be in magnitude or direction or both, usually measured in units m/s2
Term
 inertia
Definition
 the property by which objects resist changes in motion
Term
 mass
Definition
 the quantity of matter in an object. more specifically, it is the measure of the inertia or sluggishness that an object exhibits in response to any effort made to start it, stop it, deflect it, or change in any way its state of motion
Term
 mechanical force
Definition
 net force=zero
Term
 support (normal) forces
Definition
 the force that suports an object against gravity, often called the normal force
Term
 Newton's first law of motion
Definition
 every object continues in a state of rest or unified speed in a straight line unless acted on by a nonzero force   an object is going to move in a straight line unless acted upon by another force greater than zero
Term
 Newtons second law of motion
Definition
 acceleration≈ net force/mass   the acceleration produced by a net force on an object is directly proportional to the net force, is in the same direction as the net force and is inversely proportional to the mass of the object   acceleration depends the force acted upon the object as well as the mass of the object
Term
 Newton's 3rd law of motion
Definition
 whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first   when 2 objects collide they exert an equal yet opposite reaction
Term
 nature of free fall
Definition
 falling only under the influence of gravity--falling without air resistance    acceleration= change in speed/time interval 10 m/s ÷ 1s=10 m/s2
Term
 force
Definition
 a push or a pull needed to start moving an object
Term
 air resistence
Definition
 when an object falls downward through the air, the force of friction acts upward
Term
 conservation of momentum
Definition
 in the absence of an external force, the momentum of a system remains unchanged.    mv(before event)=mv(after event)
Term
 the relationship of impulse and momentum
Definition
 Ft=Δ(mv) change in momentum  1. increasing momentum:apply the greatest force possible for as long as possible 2. decresing momentum over a long time:extend the time during which your momentum is brought to zero 3. decreasing momentum over a short time:short impact times=larger impact forces
Term
 role of momentum in collisions
Definition
 when objects collide 1. elastic: conservative (bounces back) 2. inelastic:nonconservative (sticks) net momentum(before collision)=net momentum(after collision) whenever objects collide in the absence of external forcesthe net momentum of both objects before the collision equals the net momentum of both objects after the collisions
Term
 Galileo and his method of science
Definition
 an object will maintain inertia constantly. he thought an object moving down a line will move in a line forever unless acted upon by an external object.
Term
 work and energy
Definition
 energy: the ability to DO WORK! work: how much force you put on an object and how long  force x distance=work
Term
 Kinetic Energy
Definition
 KE=½mass x speed2 energy of motion
Term
 potential energy
Definition
 resting energy it is stored and held in readiness
Term
 power
Definition
 equal to the amount of work done per time it takes to do it   power= work done/time interval
Term
 conservation of energy
Definition
 energy cannot be created or destroyed; it may be transformed from one form to another, but the total amount of energy never changes
Term
 machine
Definition
 device for multiplying forces or simply changing the direction of forces
Term
 lever
Definition
 simple machine consisting of a rigid rod pivoted at a fixed point called the fulcrum
Term
 conservation of energy for machines
Definition
 the work output of any machine cannot exceed the work imput.  workinput=workoutput (Fd)input=(Fd)output
Term
 law of universal gravitation
Definition
 every body in the universe attracts every other body with a force that, for two bodies, is directly proportional to the square of the of the distance separating them F=G(m1m2/d2)
Term
 celestial gravity
Definition
 fifth element, perfect motion-perfect circle
Term
 terrestrial gravity
Definition
 fire, water, water, earth four elements
Term
 inverse-square laws
Definition
 the intensity of an effect from a localized source spreads uniformly throughout the surrounding space and weakens the inverse square of the distance   intensity= 1/distance2
Term
 weightlessness
Definition
 being without a support force as in free fall
Term
 tides and their causes
Definition
 neap tides: waxing 1/2 moon and waning 1/2 moon   spring tides: when moon, earth, and sun are lined up; new and full moon
Term
 motion of projectiles
Definition
 any object that moves through the air or through space under the influence of gravity
Term
 which quantities are vectors, how vectors are described, how vectors are added or subtracted
Definition
 -quantities have 2 parts, size and direction  -velocity, acceleration, & force are all vectors -quantities that only have size are referred to as scalar -add in geometric fashion to yield the resultant
Term
 ellipse
Definition
 the oval path followed by a satellite. sum of the distances from any point on the path to two points called foci is a constant. when the foci are together at one point, the ellipse is a circle. as the foci get farther apart, the ellipse becomes more eccentric.
Term
 Kepler's First Law of Planetary Motion
Definition
 1. each planet moves in eliptical orbits with the sun at one focus 2. the line from the planet to the sun sweeps out equal areas in equal time;a planet moves faster when it is closer to the sun and slower when it is further away. 3.The square of the orbital period (T2) is proportional to cube of the average distance form the sun (R3) [ T2 ~ R3 ] a planet that orbits with a large radius moves much slower than a planet with a smaller orbital radius.
Term
 Kepler's Third Law of Planets in Motion
Definition
 3.The square of the orbital period (T2) is proportional to cube of the average distance form the sun (R3) [ T2 ~ R3 ] a planet that orbits with a large radius moves much slower than a planet with a smaller orbital radius.
Term
 Kepler's Second Law of Planets in motion
Definition
 2. the line from the planet to the sun sweeps out equal areas in equal time;a planet moves faster when it is closer to the sun and slower when it is further away.
Term
 escape speed
Definition
 the speed that a projectile, space probe, or similar object must reach to escape the gravitational influence of Earth or of another celestial body to which it is attracted
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