Motion, Speed, Motion, Speed, Velocity and Velocity and AccelerationAcceleration

MotionMotion

►MotionMotion – an object’s change in – an object’s change in position relative to a reference pointposition relative to a reference point

SpeedSpeed

►SpeedSpeed is the distance traveled divided is the distance traveled divided by the time interval during which the by the time interval during which the motion occurred. S= D/Tmotion occurred. S= D/T

►Normally, objects do not travel at a Normally, objects do not travel at a constant speedconstant speed

►Average Speed - Average Speed - total distancetotal distance

total timetotal time

VelocityVelocity

►VelocityVelocity is the speed of an object in a is the speed of an object in a particular directionparticular direction

► Imagine two birds leave the same tree Imagine two birds leave the same tree at the same time. The both fly at at the same time. The both fly at 10km/hr for 5 minutes. Why don’t 10km/hr for 5 minutes. Why don’t they end up at the same place?they end up at the same place?

VelocityVelocity

►VelocityVelocity appears to be very similar to appears to be very similar to speed, however, when describing the speed, however, when describing the velocity of an object you need to velocity of an object you need to provide a magnitude and a directionprovide a magnitude and a direction

►MagnitudeMagnitude – the speed of the object – the speed of the object►DirectionDirection – the direction the object is – the direction the object is

movingmoving

AccelerationAcceleration

►AccelerationAcceleration is the rate at which is the rate at which velocity changes over timevelocity changes over time An object accelerates if its speed, direction, An object accelerates if its speed, direction,

or both changeor both change

►Average acceleration = final velocity – starting

velocitytime it takes to change

velocity

AccelerationAcceleration

►ExampleExample A car on the highway is traveling 55 mi/hr A car on the highway is traveling 55 mi/hr

and it passes another car. In order to and it passes another car. In order to pass, the car has to accelerate to 65 pass, the car has to accelerate to 65 mi/hr. The car reaches this velocity 40 mi/hr. The car reaches this velocity 40 seconds later. What is the average seconds later. What is the average acceleration of the car?acceleration of the car?

Acceleration and VelocityAcceleration and Velocity

►http://www.glenbrook.k12.il.us/GBSSCI/PHYS/mmedia/kinema/avd.html

►As velocity As velocity increasesincreases, so does , so does accelerationacceleration

►As velocity As velocity decreasesdecreases, so does , so does accelerationacceleration

►When direction changes, so does When direction changes, so does accelerationacceleration

►When there is a When there is a constant velocityconstant velocity, , there is no accelerationthere is no acceleration