Physics vocabulary for chapters 1-5

physics

a branch of science that involves the study of the of the physical world: energy, matter, and how they are related

dimensional analysis

the methos of treating units as algebraic quantities, which can be cancelled

significant digits

valid digits for measurement

model

a representation of an idea, event, structure, or object to help people better understand it

scientific method

making observations, doing experiments, and creating models or theories to support your results

hypothesis

an educated guess about how variables are related

scientific law

a rule of nature that sums up related observations to describe a pattern in nature

scientific theory

an explanation based on many observations supported by experimental results

measurement

a comparison between an unknown quantity and a standard

precision

the degree of exactness of a measurement

accuracy

how well the results of a measurement agree with the "real" value

independent variable

the factor that is changed or manipulated during an experiment

dependent variable

the factor that depends on the independent variable

line of best fit

a line drawn as close to all points as possible to better model the data

linear relationship

y=mx+b

quadratic relationship

y=ax^2+bx+c

inverse relationship

y=a/x

instantaneous velocity

the speed and direction of an object at a particular instant

magnitude

the size of a quantity

position

the location of an object relative to an origin

time interval

the formula t(f)-t(i) represents this

vector

a quantity with both magnitude and direction

average velocity

ratio of the change in position to the time interval during which the change occurred

coordinate system

a system that defines the zero point of the variable you are studying

origin

the zero point is also called the

position-time graph

a graph with time data on the horizontal axis and position data on the vertical axis

motion diagram

this shows a series of images showing the position of a moving object over equal time intervals

resultant

a vector that represents the sum of two or more vectors

particle model

a simplified motion diagram that shows the object in motion as a series of points

distance

a scalar quantity that is the length, or size, of the displacement vector

scalar

a quantity that has only magnitude

instantaneous position

the location of an object at a particular instant

displacement

the vector quantity that defines the distance and direction between two positions

average speed

the absolute value of the slope on a position-time graph

acceleration

the rate at which the velocity of an object changes

velocity-time graph

a graph that can be used to plot the velocity of an object versus time and to determine the sign of an objects acceleration

average acceleration

the change in an object's velocity during a measurable time interval, divided by that specific time interval; is measured in m/s^2

instantaneous acceleration

the change in an object's velocity at a specific instant of time

free fall

the motion of a body when air resistance is negligible and the motion can be considered due to the force of gravity alone

free-fall acceleration

the acceleration of an object due only to the effect of gravity

force

A push or pull exerted on an object that causes a change in motion; has both direction and magnitude and may be a contact or a field force

system

object or objects of interest that can interact with each other and the external world

free-body diagram

A physical model that represents the forces acting on a system

net force

the vector sum of all the forces on an object

Newton's second law

States that the acceleration of an object is proportional to the net force and inversely proportional to the mass of the object being accelerated

Newton's first law

States that an object at rest will remain at rest, and a moving object will continue moving in a straight line with constant speed, if and only if the net force acting on that object is zero

inertia

The tendency of an object to resist change

equilibrium

The condition in which the net force on an object is zero

weight

the gravitational force experienced by an object

gravitational field

the vector quantity that relates the mass of an object to the gravitational force it experiences at a given location; represented by the symbol g

apparent weight

The force experienced by an object, resulting from all the forces acting on it, giving the object an acceleration

weightlessness

An object's apparent weight of zero that results when there are no contact forces pushing up on the object

drag force

The force exerted by a fluid on an object moving through the fluid; depends on the object's motion and properties and the fluid's properties

terminal velocity

The constant velocity of an object that is reached when the drag force equals the force of gravity

interaction pair

A pair of forces that are equal in strength, but opposite in direction

Newton's third law

States that all forces come in pairs and that the two forces in a pair act on different objects and are equal in strength and opposite in direction

tension

The specific name for the force exerted by a rope or a string

normal force

The perpendicular contact force exerted by a surface on another object

components

projections of a vector parallel to the x-axis and another parallel to the y-axis

vector resolution

the process of breaking down a vector

kinetic friction

the foce exerted on one surface by a second surface when the two surfaces rub against each other because one or both od the surfaces are moving

static friction

the force exerted on one surface by a second surface when there is no motion between the two surfaces

coefficient of kinetic friction

the slope of a line on a kinetic friction force v. normal force graph. relates frictional force to normal force and depends on the two surfaces in contact. it is needed to calculate kinetic friction

coefficient of static friction

a dimensionless constant depending on the two surfaces in contact. it is used to calculate the maximum static friction that needs to be overcome before motion begins. It is larger than the coefficient of kinetic friction

equilibrant

a force that places an object in equilibrium; the same magnitude as the resultant but opposite direction