close agreement by competent observers who make a series of observations of the same phenonmenon
Laws or Principles
when hypotheses about the relationship among natural quantities are tested over and over again and not contradicted, may become...
a synthesis of a large body of information that encompasses well-tested and verified hypotheses about certain aspects of the natural world
quantity that needs both magnitude and direction for a complete description (Ex: force)
quantity that can be described by magnitude only and has no direction (Ex: time, area, and volume)
whenever the net force on an object is zero the object is said to be in mechanical equilibrium
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.
measure of the amount of material (matter) in an object and depends only on the number of and kind of atoms that compose it
the speed at any instant (tell speed of a car any instant by looking at speedometer)
any object that moves through the air or space, acted on only by gravity (and air resistance, if any).
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)
friction acting on something moviing through the air, a common form of fluid friction.
pressure is measured in newtons per square meter. Equal to one newton per square newton.
speed at which the acceleration of a falling object is zero because friction balances the weight