Part 1: Motion

can you tell if velocity is positive, negative, zero

the velocity is the slope of the line on a position vs time graph zero = flat line positive = positive slope negative = negative slope

change in time

change in position divided by velocity

what is its displacement over a certain time interval

change in position over a period of time

that when an object is thrown in the air or dropped from a height above the earth, unless there is a lot of air resistance, it automatically has an acceleration equal to -9.8m/s^2

acceleration due to gravity the rate of falling for all objects is the same regardless of weight

constant velocity means

acceleration is zero

is velocity constant or is the object accelerating

acceleration results in curve on graph constant speed is sloped line steeper slope as velocity increases

what acceleration, average acceleration and instantaneous acceleration are

acceleration: change in velocity change in velocity divided by change in time m/s^2 can be + or - constant velocity = 0 acceleration

How to add two vectors together and find the magnitude and direction of the resultant vector

add and subtract components of vectors x and y

that free fall acceleration, the acceleration due to gravity is constant

and always pointing down (toward the earth) up: -9.8m/s^2 down: 9.8m/s^2

when an object thrown in the air reaches its maximum height it has a vertical velocity of 0m/s^2

assume zero initial position and velocity unless problem explicitly gives you them A falling object reaches terminal velocity when the upward force of air resistance on the object equals the object's weight

how to use a position vs time graph to find average and or instantaneous velocity

average velocity: total displacement (distance) traveled divided by the total time taken instantaneous velocity: slope of position vs time graph at a moment

how to find average and or instantaneous acceleration using a velocity vs time graph

average: change in velocity / change in time instantaneous: slope of tangent line

is the object speeding up or slowing down

based on acceleration of line slowing down = negative speeding up = positive

direction from components

(0)=tan^-1(Fy/Fx) 360 - ^ = direction in degrees

magnitude of a vector

(Fx, Fy) use pythagorean theorem

examples of free fall

- a ball falling down with negligible air friction - a ball thrown up with negligible air friction - a ball launched at any angle, even horizontally as long as their is negligible air friction always goes downwards - when nothing is touching it and gravity is the only force on object

time conversions

1 millisecond = 0.001s 60 seconds = 1 minute 60 minutes = 1 hour 1 day = 24 hours = 86,400s 1 year = 365.24 days = 31,579,200 s

how to use kinematics equations to solve problems involving constant acceleration or free fall

1. v final = v initial + acceleration x change in time 2. displacement = 1/2(v final + v initial) x change in time 3. v final^2 = v initial^2 + 2a deltax 4. displacement = vi deltat + 1/2a x deltat^2

is the object accelerating is the acceleration constant what does the slope represent

constant acceleration is a straight line of constant slope also means that change in velocity each second is the same positive slope = positive acceleration negative slope = negative acceleration

velocity equals

displacement (change in position) divided by change in time

the difference between displacement and distance traveled

displacement: change in position can have positive (right) and negative (left) values distance traveled: space between any two points; a measurement of length, height, meters, feet, inches, cm

how to draw and/or interpret a motion diagram

equally spaced: constant speed increasing distance: speeding up decreasing distance: slowing down

how much distance has it traveled

final position d = velocity x time + 1/2acceleration x time

average velocity

final position - initial position / total time

position is equal to the object's starting position plus displacement

final position = initial position + displacement

component force

force that lies along one of the three coordinate axes (x, y, or z). vector in the x-direction is Fx and is found by drawing a perpendicular line from the head of the vector to the x-axis. y-component Fy is similarly found by drawing a perpendicular line to the y-axis the force vector F1→F1→ = (+4,+2) N points in the opposite direction from the vector F2→F2→ = (−4,−2) N.

vector diagram

includes direction, strength, size graphical representation of a vector in which the coordinate axes are scaled to represent the components of the vector in perpendicular directions. magnitude of force vector: length on diagram, strength in N cannot be negative ^

understand the motion of projectiles and be able to analyze the vertical and horizontal components of the motion of projectile.

know that the vertical and horizontal components of a projectile's motion are independent, and that the only variable which connects the two parts of the motion is time. understand that this idea is key for solving projectile motion problems.

how to draw a best fit line and calculate the slope of a line

m = (y2 - y1)/(x2 - x1), to find the slope

what does a negative slope represent what does a negative slope mean

negative velocity traveling backwards

when acceleration is unknown

position = initial position + 1/2(initial velocity = velocity) x time

deriving position

position = initial position + initial speed x time + 1/2 acceleration x time

constant velocity motion

position at time = initial position at time t=0 + (velocity)(time)

How to convert between units in the metric system, and how to convert units of time

positive physics

how to interpret position vs time graph

represents motion position = y axis time = x axis

the difference between a vector and a scalar + examples

scalar: a quantity that only has a magnitude (single value, no units) ex: distance, speed, time, mass, energy, work, density, distance, temperature vector: a quantity that has a direction + magnitude ex: position, displacement, velocity, acceleration, force, momentum - positive means right - negative means left magnitude of vector: it's length independent of direction displacement of -10m has magnitude of 10m cannot be negative

velocity is constant when

speed is a flat line

distance equals

speed x time

the difference between speed and velocity

speed: ratio of distance traveled to time taken (m/s or mph) velocity: the rate at which position changes (can be + or -) speed w direction

for what part of the graph is the speed greatest

steep slope

what is acceleration

the slope of the velocity vs time graph

how to resolve (break) a vector into its horizontal and vertical components

use middle line force times cosangle for horizontal (fx) use middle line force time sinangle for vertical (fy)

instantaneous velocity

velocity = initial velocity + acceleration x time

how to interpret a velocity vs time graph: can you tell by looking at it (page 111)

velocity = y axis time = x axis Objects reverse direction when their velocity becomes zero and then change sign area under graph is an accelerating object's displacement

displacement

velocity x change in time

when time is not known

velocity^2 = initial velocity^2 + 2(acceleration)(position - final position)

when is an object slowing down, speeding up

when sign of velocity and acceleration differ ex: acceleration of -1m/s^2 adds -1m/s to velocity decreases a positive velocity makes negative velocity more negative and faster