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45 terms

Conceptual Physics 2009: Unit 1 (Ch 1-7)

Based on the newest Paul Hewitt conceptual physics textbook, published 2009
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Scientific methods
effective in gaining, organizing, and applying new knowledge
Fact
close agreement by competent observers who make a series of observations of the same phenonmenon
Hypothesis
educated guess that is not fully accepted until demonstrated by experiment
Laws or Principles
when hypotheses about the relationship among natural quantities are tested over and over again and not contradicted, may become...
theory
a synthesis of a large body of information that encompasses well-tested and verified hypotheses about certain aspects of the natural world
force
a push or pull
net force
combination of all forces acting on an object
magnitude
amount
vector
an arrow that represents the magnitued and direction of a quantity
vector quantity
quantity that needs both magnitude and direction for a complete description (Ex: force)
scalar quanity
quantity that can be described by magnitude only and has no direction (Ex: time, area, and volume)
Mechanical equilibrium
state wherein no physical changes occur
Equilibrium rule
whenever the net force on an object is zero the object is said to be in mechanical equilibrium
Support force
the upward force that balances the weight of an object on a surface
Resultant
the sum of two or more vectors
Friction
force that acts between materials that touch as they move past each other
Inertia
the property of a body to resist changes to its state of motion
Newton's first law (law of intertia)
Newton's first law states that every object continues in a state of rest, or of uniform speed in a straight line, unless acted on by a nonzero net force.
kilograms
the fundamental unit of mass
Mass
measure of the amount of material (matter) in an object and depends only on the number of and kind of atoms that compose it
Weight
measure of the gravitational force acting on the object. Depends on object's location
Newton
SI unit of force (1kg=10N)
Relative
in respect to (An object is moving if its position, relative to a fixed point, is changing
Speed
how fast an object is moving
instantaneous speed
the speed at any instant (tell speed of a car any instant by looking at speedometer)
average speed
the total distance covered divided by time
Velocity
how fast and in what direction an object moves
Acceleration
rate at which velocity is changing. Change of velocity/time interval
Free fall
when an object is only affect by the force of gravity
Elapsed time
time that has elapsed, of passed, since the beginning of any motion
components
two vectors at right angles that add up to a given vector
resolution
process of determining the components of a vector
projectile
any object that moves through the air or space, acted on only by gravity (and air resistance, if any).
trajectory
the path of a projectile
Inversely
two values change in opposite directions. Mathematically we see that as the denominator increases, the whole quantity decreases by the same factor.
Newton's Second Law
the acceleration produced by a net force on an object is directly proportional to the marnitue of the net force, is in the same direction as the net force, and is inversely proportional to the mass of the object. Acceleration = net force/mass (a=F/m)
fluids
liquids and gases
air resistance
friction acting on something moviing through the air, a common form of fluid friction.
Free body diagram
diagram showing all the forces acting on an object
pressure
the amount of force per unit of area. Pressure = force/area of application (P=F/A)
Pascals (Pa.)
pressure is measured in newtons per square meter. Equal to one newton per square newton.
Terminal speed
speed at which the acceleration of a falling object is zero because friction balances the weight
Terminal velocity
terminal speed combined with non changing direction of motion
Interaction
a mutual action between one thing and another
Newton's third law
whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object. One force is called the action force and the other the reaction force