this is an ppt, for specially for that childrens that cant understand topics of basic o level physics .....

1. Motion, Speed, VelocityMotion, Speed, Velocity
and Accelerationand Acceleration

2. MotionMotion
►MotionMotion – an object’s change in position– an object’s change in position
relative to a reference pointrelative to a reference point

3. Reference PointReference Point
►The Earth’s surface is used as a commonThe Earth’s surface is used as a common
reference pointreference point
►A moving object can be used as a referenceA moving object can be used as a reference
point as wellpoint as well

4. SpeedSpeed
►SpeedSpeed is the distance traveled divided byis the distance traveled divided by
the time interval during which the motionthe time interval during which the motion
occurredoccurred
►Normally, objects do not travel at a constantNormally, objects do not travel at a constant
speedspeed
►Average Speed -Average Speed - total distancetotal distance
total timetotal time

5. Which Distance?Which Distance?
► Farmer Jones drives 6 miles down a straight road.Farmer Jones drives 6 miles down a straight road.
She turns around and drives 4 miles back. WhatShe turns around and drives 4 miles back. What
was her average speed for this trip if it took 1was her average speed for this trip if it took 1
hour?hour?

6. Your answer to this problem dependsYour answer to this problem depends
on your interpretation of "distanceon your interpretation of "distance
traveled". You could say:traveled". You could say:
► TheThe total distancetotal distance traveled by Farmer Jones is 10traveled by Farmer Jones is 10
miles. Therefore her average speed is 10 mi/hr.miles. Therefore her average speed is 10 mi/hr.
► TheThe net distancenet distance traveled by Farmer Jones is 2 miles.traveled by Farmer Jones is 2 miles.
Therefore, her average speed is 2 mi/hr.Therefore, her average speed is 2 mi/hr.
► There are good reasons to use either interpretation - it'sThere are good reasons to use either interpretation - it's
mostly a matter of preference. We will interpret "distancemostly a matter of preference. We will interpret "distance
traveled" to betraveled" to be net distancenet distance ((also calledalso called
displacement).displacement). Farmer Jones' average speed was 2Farmer Jones' average speed was 2
mi/hr.mi/hr.

7. VelocityVelocity
►VelocityVelocity is the speed of an object in ais the speed of an object in a
particular directionparticular direction
►Imagine two birds leave the same tree atImagine two birds leave the same tree at
the same time. The both fly at 10km/hr for 5the same time. The both fly at 10km/hr for 5
minutes. Why don’t they end up at theminutes. Why don’t they end up at the
same place?same place?

9. VelocityVelocity
►VelocityVelocity appears to be very similar toappears to be very similar to
speed, however, when describing thespeed, however, when describing the
velocity of an object you need to provide avelocity of an object you need to provide a
magnitude and a directionmagnitude 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

10. VelocityVelocity
►Ex) A bus has a velocity of 35miles/hrEx) A bus has a velocity of 35miles/hr
heading westheading west

11. Resultant VelocityResultant Velocity
►An object can have a resultant velocity if it isAn object can have a resultant velocity if it is
experiencing more than one motion.experiencing more than one motion.
►For example if a person walks down theFor example if a person walks down the
center of a bus while it is in motion there arecenter of a bus while it is in motion there are
two velocities occurring.two velocities occurring.
 1. The movement of the bus1. The movement of the bus
 2. The movement of the person inside the bus2. The movement of the person inside the bus

12. ExampleExample
15 m/s + 1 m/s = 14 m/s

13. ExampleExample
15 m/s + =1 m/s 16 m/s

14. AccelerationAcceleration
►AccelerationAcceleration is the rate at which velocityis the rate at which velocity
changes over timechanges over time
 An object accelerates if its speed, direction, orAn object accelerates if its speed, direction, or
both changeboth change
►Average acceleration =
final velocity – starting
velocity
time it takes to change
velocity

15. AccelerationAcceleration
►ExampleExample
 A car on the highway is traveling 55 mi/hr and itA car on the highway is traveling 55 mi/hr and it
passes another car. In order to pass, the carpasses another car. In order to pass, the car
has to accelerate to 65 mi/hr. The car reacheshas to accelerate to 65 mi/hr. The car reaches
this velocity 40 seconds later. What is thethis velocity 40 seconds later. What is the
average acceleration of the car?average acceleration of the car?

16. Acceleration and VelocityAcceleration and Velocity
►http://www.glenbrook.k12.il.us/GBSSCI/PHYS/mhttp://www.glenbrook.k12.il.us/GBSSCI/PHYS/m
►As velocityAs velocity increasesincreases, so does, so does
accelerationacceleration
►As velocityAs velocity decreasesdecreases, so does, so does
accelerationacceleration
►When direction changes, so doesWhen direction changes, so does
accelerationacceleration
►When there is aWhen there is a constant velocityconstant velocity , there, there
is no accelerationis no acceleration