Dr. Roz: CP Physics Midterm

physics

the study of the fundamental laws of nature

science

an organized way of thinking about nature and understanding how it works

scientific method

the systematic approach scientists use to learn about the laws of nature

observation

starting point of any scientific investigation in which you describe events in a logical and orderly way

inference

a logical interpretation of your observations

hypothesis

a detailed scientific explanation for a set of observations that can be verified or rejected by careful experiments

independent variable

the variable you change in the experiment

dependent variable

the variable you measure to see how it depends on the independent variable

theory

a detailed explanation of some aspect of nature that accounts for a set of well tested hypotheses

its ability to account for known observations and to correctly predict new observations

what is the validity of a hypothesis based on?

a small number of fundamental laws and principles

what is physics based on?

observations, a hypothesis, and experiments designed to verify the hypothesis

what does scientific method involve?

the hypothesis must be revised

what happens if the experiment results don't match up with the hypothesis?

metric system

what is the common system of measurement?

bias

a preference for a particular point of view for personal rather than logical or scientific reasons

peer review

the process in which a report is sent to several experts in the field to look for errors, biases, and oversights

meter

the base unit of length

seconds

the base unit of time

kilogram

the base unit of mass

SI unit

the unit system also known as the Systeme International d'Unites

mass

a measure of the amount of matter in an object

weight

a measure of the gravitational force acting on an object and varies depending on the object's location

dimensional analysis

a type of calculation written in terms of dimensions

base unit

what is the standard "measuring stick" for a physical quantity referred to as?

equation

a mathematical expression that relates physical quantities

accuracy

a measure of how close the measured value of a quantity is to the actual value

precision

a measure of how close together the values of a series of measurements are to one another

significant figures

the number of digits that are actually measured plus one estimated digit

scientific notation

a method used to express numerical values as a number between 1 and 10 times an appropriate power of 10

linear relationship

the relationship that exists between two quantities that form a straight line on a graph

parabola

a curved shape on a graph, indicating that one quantity depends on the square of another

inverse relationship

the relationship between two quantities in which one gets larger as the other gets smaller

scalar

a quantity represented by a numerical value and a unit

speed

a scalar quantity that describes the rate of motion

vector

a quantity consisting of both a numerical value with its unit and a direction

velocity

a vector quantity that describes the rate of motion and its direction

length, speed, acceleration, or time duration

a physical quantity is a property of a physical system that can be measured in what?

to save time and effort when writing out very large and very small numbers

why is scientific notation used?

coordinate system

a frame of reference used to describe a system or an event

distance

the total length of the path taken on a trip

displacement

the change in position of an object

subtracting the initial position from the final position

how is displacement calculated?

the rate of motion and its direction

what does velocity give?

average speed

the speed of an object averaged over a given period of time

speed gives the rate of motion

what does speed give?

average velocity

the displacement of an object per unit of time

when the displacement is in the positive direction

when is average velocity positive?

when the displacement is in the negative direction

when is average velocity negative?

a position-time graph of the motion

what does plotting the position data on the y axis and the time data on the x axis create?

slope

the rise over the run for a line on a graph

motion with constant velocity

what does a position-time graph that is a straight line correspond to?

the position-time equation of motion gives its position x at any time t

if the initial position and the constant velocity of an object are known, what happens to the equation?

the time at which the objects are at the same location

what does the intersection of the graphs of two equations of motion for two different objects represent?

acceleration

the rate at which velocity changes with time

average acceleration

the change in velocity divided by the change in time

instantaneous acceleration

the acceleration of an object at a given instant of time

constant acceleration

the acceleration is the same at every instant of time

a straight line with a slope equal to the acceleration

what is the velocity-time graph of an object with constant acceleration?

velocity and acceleration

speed increases when what two things have the same sign?

equal to the sum of the initial and final velocities divided by 2

when the acceleration is constant, the average velocity is equal to what?

the area under its velocity-time curve

the distance traveled by an object is equal to what?

a parabolic position-time graph

what does constant acceleration produce?

whether the parabola has an upward or downward curvature

the sign of the acceleration determines what?

free fall

motion that is determined by gravity alone

constant acceleration

Galileo concluded that if the effects of air resistance can be ignored, then all objects in free fall have the same what?

the effects of air resistance are small enough to ignore

the motion of an object can be treated as free fall whenever what?

9.81 m/s^2

what is acceleration due to gravity on Earth?

vector quantity

a quantity that is specified by both a length and a direction

magnitude

the length of a vector

to find its components

what does it mean to resolve a vector?

the lengths of the vector along specified directions

what are a vectors components?

magnitude and direction or in terms of their x and y components

vectors can be specified in terms of their what?

resultant

the result of adding two or more vectors

place the tail end of one to the head of another

how do you place vectors when adding them?

relative motion

the motion of one object relative to another object

if you know the velocity of each object relative to a third object

how can you can relate the velocities of two objects to each other?

the addition of vectors

how are relative velocities determined?

projectile

an object thrown, kicked, batted, or otherwise launched into motion and then allowed to follow a path determined solely by the influence of gravity and makes a parabolic path

range

the horizontal distance traveled by a projectile before it lands

45

at what angle does maximum range occur?

independently

components of motion in the x and y directions can be treated independently or dependently of one another?

force

a push or pull

net force

the vector sum of the individual forces acting on an object

inertia

the tendency of an object to resist any changes in its motion

Newton

a unit of force

Newton's First Law

an object moving with constant velocity continues to move with the same speed and in the same direction as long as no net force acts on it (an object at rest remains at rest as long as no net force acts on it)

Newton's Second Law

the sum of the forces (net force) acting on an object is equal to its mass times it's acceleration

Newton's Third Law

for every action force acting on an object, there is a reaction force acting on a different object/the action and reaction forces are equal in magnitude and opposite in direction

its mass times its acceleration

the sum of the forces (net forces) acting on an object is equal to what?

free body diagram

a sketch that shows all the forces acting on an object

normal force

a force exerted perpendicular to the surface of contact

apparent weight

the sensation of having a different weight due to a force being exerted on a person; due to the force exerted through contact with the floor

Hooke's law

the force exerted by an ideal spring is proportional to the distance by which it's stretched or compressed

spring constant

the constant "k" in Hooke's law; units are Newtons per meter (Nm)

tension

the force exerted by a string, rope, or wire that is pulled tight

equilibrium

a state in which an object has zero acceleration and is subject to zero net force

its mass times the acceleration due to gravity

the weight of an object is equal to what?

friction

force that opposes the motion of one surface past another

kinetic friction

friction that arises when surfaces slide against one another

static friction

force that opposes the sliding of one nonmoving surface past another