Intro to MotionIntro to Motion

Uniform and Non-Uniform Uniform and Non-Uniform MotionMotion

Speed and VelocitySpeed and Velocity

Framing QuestionsFraming QuestionsWhat is the difference between What is the difference between uniform motion and non-uniform uniform motion and non-uniform motion?motion?What are examples of each?What are examples of each?What is the difference between What is the difference between speed and velocity?speed and velocity?What are the formulas for speed and What are the formulas for speed and velocity?velocity?

Uniform MotionUniform MotionUniform motion is movement in a Uniform motion is movement in a straight linestraight line at a at a constant speedconstant speed Ex: A cyclist traveling on a straight path at a speed Ex: A cyclist traveling on a straight path at a speed

of 10m/s.of 10m/s.It is important to know how to figure out It is important to know how to figure out uniform motion because it is the uniform motion because it is the basis for the basis for the rest of physicsrest of physics… but uniform motion rarely … but uniform motion rarely existsexists How many times do you see something going at How many times do you see something going at

precisely the same speed in a precisely straight line?precisely the same speed in a precisely straight line?This being said, we will focus on uniform motion This being said, we will focus on uniform motion in grade 10 so you understand the basicsin grade 10 so you understand the basics

Non-Uniform MotionNon-Uniform MotionAny movement Any movement not in a straight linenot in a straight line or or not at a constant speednot at a constant speed is called non- is called non-uniform motionuniform motion Ex: A car traveling around a cornerEx: A car traveling around a cornerMost enduring motions are non-uniformMost enduring motions are non-uniformWe will touch on one (acceleration), but We will touch on one (acceleration), but you will continue with the rest in grade you will continue with the rest in grade 11 physics.11 physics. For now you must understand the difference For now you must understand the difference

between these concepts….between these concepts….

Exercise: Uniform or Non-Exercise: Uniform or Non-Uniform?Uniform?

A steel ball is dropped from your raised had to the floorA steel ball is dropped from your raised had to the floorA car is traveling north at a constant speed for 2 hoursA car is traveling north at a constant speed for 2 hoursA jogger is running around a circular track at a constant A jogger is running around a circular track at a constant speedspeedA car is traveling a steady 60km/h due westA car is traveling a steady 60km/h due westA leaf flutters to the groundA leaf flutters to the groundA rocket is launched from the Earth towards the moonA rocket is launched from the Earth towards the moonA motorcycle rider applies the brakes in order to come to a A motorcycle rider applies the brakes in order to come to a stopstopA ball at the end of a rope is whirled around a person’s head A ball at the end of a rope is whirled around a person’s head at a constant speed of 8.0m/sat a constant speed of 8.0m/sThe world’s fastest women compete in the 100m dash at the The world’s fastest women compete in the 100m dash at the OlympicsOlympicsA marble rolls in a straight path down the hallwayA marble rolls in a straight path down the hallway

Is there ever a time when a motion which is non-uniform Is there ever a time when a motion which is non-uniform overall, is uniform at some point?overall, is uniform at some point?

Speed, inSpeed, inSpeed describes Speed describes how fasthow fast something something is movingis movingIt is It is scalarscalar, so we indicate:, so we indicate: MagnitudeMagnitude Not directionNot directionThe standard unit for measuring The standard unit for measuring speed is speed is m/sm/s

Speed, inSpeed, inSymbols:Symbols:

SpeedSpeed = = vv Instantaneous speed (speed at a specific instant in time) Instantaneous speed (speed at a specific instant in time)

= = vvinstinst Average speed (average speed over a particular time Average speed (average speed over a particular time

interval) = interval) = vvavav

Formula:Formula: Speed = Speed = distancedistance

timetime vv = = dd tt

Example:Example: The cyclist reached a maximum speed The cyclist reached a maximum speed of 12.0 m/s during the race.of 12.0 m/s during the race.

Velocity, inVelocity, inVelocity describes the Velocity describes the speed and speed and directiondirection of motion of motion This means it describes how fast an This means it describes how fast an

object’s position is changingobject’s position is changingVelocity is a Velocity is a vectorvector, so we describe:, so we describe: MagnitudeMagnitude DirectionDirectionThe standard unit for measuring The standard unit for measuring velocity is velocity is m/sm/s

Velocity, inVelocity, inSymbols:Symbols:

Velocity = Velocity = vv Initial velocity = Initial velocity = vvii Final velocity = Final velocity = vvff Instantaneous velocity (velocity at a specific instant in time) Instantaneous velocity (velocity at a specific instant in time)

= = vvinstinst Average velocity (average velocity over a particular time Average velocity (average velocity over a particular time

interval) = interval) = vvavav

Formula:Formula: Velocity = Velocity = displacementdisplacement

timetime v = v = dd

ttExample:Example:

The aircraft was traveling at 535km/h, headed 45° north of The aircraft was traveling at 535km/h, headed 45° north of westwest

Practice ProblemPractice ProblemAn object traveling at a constant speed travels An object traveling at a constant speed travels due west for 800m in 40s.due west for 800m in 40s. What is the speed of the object?What is the speed of the object? What is the velocity of the object?What is the velocity of the object?v = d/tv = d/t v = d/tv = d/t = 800m/40s= 800m/40s = 800m due west/40s = 800m due west/40s = 20 m/s= 20 m/s = 20 m/s due west = 20 m/s due westNote: When the object goes in a straight line, the Note: When the object goes in a straight line, the magnitude for speed and velocity will always be magnitude for speed and velocity will always be the same!the same!