PPTG101213 Scalars and Vectors GALLEGO

7/31/2019 PPTG101213 Scalars and Vectors GALLEGO

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Difference between scalar and vector |Representation of vectors |Resultant vectors

28 July 2012 REDG 2011 1


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Lolo Wacko got an

invitation from a

friend for Humba

Party. He was given

this instruction:

Our house is

located 8 km from

the signage in the

cross road.Which

way should he go?

28 July 2012 REDG 2011 2

Scalar vs Vector Quantities


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Lola Wacka also got

an invitation from

a friend for the

same Humba Party.

She was given this

instruction:Our

house is located 8

km west from the

signage in the

cross road.Whichway should he go?

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Ride on the School

Bus that is 8 kmfrom the house.


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Ride on the School

Bus that is 8 km,North from the

house.


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What is the difference betweenscalar quantity and vector

quantity?


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A scalar quantity is the aquantity that is described fully by

magnitude alone.

A vector quantity is a quantity

that is described fully by both

magnitude and direction.


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These are vector quantities;

1. Displacement2. Velocity

3. Acceleration

4. Force


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A quantity which is ignorant of direction is

referred to as _______________.

A quantity which is conscious of direction

is referred to as _______________.


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28 July 2012 REDG 2011 10

Distance vs Displacement

There are two quantities which are used

to describe the changing location.

Distance- refers to the total amount of

ground covered. Denoted by

Displacement- refers to the overall

change in position from start to finish.

Denoted by


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28 July 2012 REDG 2011 11


There are two quantities which are used

to describe the changing location.

Along whichpath(s) is the

distance travelled

different from thedisplacement?

1

2

3


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You run from your house to school that is

7 km away. You then walk home.

What distance did you travel?

What is the displacement of the entire trip?


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Observe the diagram below. A person

starts at A walks along the bold path andfinishes at B. Each square is 1 km long

along its edge.

A person walks atotal distance

of_______.

This person has adisplacement of

_________.


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28 July 2012 REDG 2011 14

Distance vs DisplacementDeedee the Rider moves from location A to location B to

location C to location D. each leg of the back-and-forth motion

takes 1 minute to complete. The total time is 3 minutes.

t=0 t=2 t=3 t=1

What is the total distance travelled by Deedee the Rider in the

3 minutes of driving?


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t=0 t=2 t=3 t=1

What is his displacement in from t=0 to t=1?


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t=0 t=2 t=3 t=1



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t=0 t=2 t=3 t=1



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t=0 t=2 t=3 t=1

What is the net displacement of Deedee the Rider in his 3-

minute joy drive?


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Change in distance (d) or change in

displacement () can be computed

d = |df-d

i|

= -


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Representing Displacement

All that are above is

NORTH


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All that are above isSOUTH


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All that are to the left isWEST


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All that are to the right isEAST


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25 meters, 30o North of East (N of E)

always indicate

the description of

the vector

use scale

1cm=10m


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28 July 2012 REDG 2011 26


50 meters, 40o North of West (N of W)

always indicate

the description of

the vector

use scale

1cm=10m


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28 July 2012 REDG 2011 27


Illustrate the following vectors using

appropriate scaling.

1. 30 meters 30o west of north

2. 50 m, 40o east of south

3. 10 m, 60

o

south of west

always indicate the description

of the vector

use scale 1cm=5m


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28 July 2012 REDG 2011 28


Illustrate the following vectors using

appropriate scaling.

1. 30 meters 30o west of north

2. 50 m, 40o east of south

3. 10 m, 60

o

south of west

always indicate the description

of the vector

use scale 1cm=5m


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28 July 2012 REDG 2011 29

Speed vs Velocity

These are two quantities which are used

to describe motion:

Speedis a quantity which describes how fast or

how slow the object is moving.

Velocity- is a quantity which describes how fast or

how slow and to what direction is the object moving.


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28 July 2012 REDG 2011 30

Speed vs Velocity

Path A

Path B

Path C

Suppose you are

considering 3 paths(A, B and C)

between the same

two locations.

Along which path

do you have to

move with the

greatest speed toarrive at the

destination at the

same amount of

time?


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Speed vs Velocity

distanceAverage speed (v) =

time

displacementAverage velocity (v ) =

time


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Speed vs Velocity

Path A

Path B

Path C

Suppose that you

run for 1 minutealong three

different paths.

Rank the three

paths from the

lowest to the

greatestspeed.


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Speed vs Velocity

Path A

Path B

Path C

Suppose that you

run for 10 secondsalong three

different paths.

Rank the three

paths from the

lowest to the

greatestvelocity.


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Speed vs Velocity

What is the unit of speed?

What is the unit for velocity?


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Speed vs Velocity

Each side of the square is 1 meter per second

A plane that is travelling at 70m/s

is influenced by a wind that blows

at a speed of 7m/s. What effect

does it give to the plane?

A plane that is travelling at 70m/s

to the east is influenced by 7m/stailwind. What effect does it give to

the plane?


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Speed vs Velocity

Each side of the square is 1 meter per second

What is the difference between

7 meters per second to the east

and

7 meters per second to the west?


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l


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S d V l i


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Speed vs Velocity

Each side of the square is 1 meter

per second

What is the difference between

7 meters per second to the east

and7 meters per second to the west?

S d V l i


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28 July 2012 REDG 2011 41

Speed vs Velocity

You run from your house to school that is 7 km away

for 30 minutes. Then you immediately to go taking 1hour in walking.

What is the average speed(in kilometer per hour) of

the entire trip?

S d V l i


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28 July 2012 REDG 2011 42

Speed vs Velocity

You run from your house to school that is 7 km away

for 30 minutes. The you immediately to go taking 1hour in walking.

What is the average velocity(in kilometer per hour)

of the entire trip?

S d V l it


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28 July 2012 REDG 2011 43

Speed vs VelocityDeedee the Rider moves from location A to location B to



t=0 t=2 t=3 t=1

Calculate the average speed and velocity (in meters per

minute) of the three-minute drive.

S d V l it


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28 July 2012 REDG 2011 44

Speed vs Velocity

Is it possible for an object to be moving at a

high speed and end up with no overall changein position?

If YES, describe an example.

If NO, why?

A l ti


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Acceleration

Acceleration is the rate of change ofvelocity.

How will the velocity change?

A l ti


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Acceleration

Velocity = speed + direction

Cite instances where speed changes ?

A l ti


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28 July 2012 REDG 2011 47

Acceleration

Velocity = speed + direction

Is it possible for an object to be accelerating

without changing its speed?

If YES, cite a situation.

If NO, explain.

A l ti


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28 July 2012 REDG 2011 48

Acceleration

Rule of Thumb

The direction of the acceleration of anobject that is moving in straight line and

slowing down is opposite to the

direction the object is moving.

What is the direction of the acceleration

of an object that is moving in a straight

path and is speeding up?

Acceleration


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28 July 2012 REDG 2011 49

Acceleration

Tell the direction (left, right, up, down, east, west,

north or south) of the acceleration in the

example below:

A car is moving eastward along Lake Avenue

and increasing its speed from 40 km per hour

to 70 km per hour.

Acceleration


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Acceleration



example below:

A northbound car skids to stop to avoid a

reckless driver.

Acceleration


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Acceleration



example below:

An Olympic diver slows down after splashing

into the water.

Acceleration


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Acceleration



example below:

A southward-bound free kick of Don Bosco

Team is slowed down and stopped by USC

Team.

Acceleration


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Acceleration



example below:

A downward falling parachutist pulls the chord

and rapidly slows down.

Acceleration


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Acceleration



example below:

A falling-bungee jumper slows down at she

nears concrete sidewalks below.

Force


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Force

Force


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Force

Representing Vectors


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In illustrating vectors, the length of the arrow

representing them is scaled down so that theproportion with other vectors is preserved.

Real size of the vector is represented by a shorter size. For

instance, 1cm: 10km



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displacement

velocity

force

acceleration

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Vector Notations



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Illustrate the following vectors in a single

graph

= 200km, 45o N of E

= 75km, 30o S of W

= 100km, 25o W of N

= 125km, 60o E of S



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A curious students was

patiently observing themotion of an ant crawling

on the floor. The ant

traveled 7 cm due east

then 3cm due north, then

4 cm due east, then 7cmdue north, then 8 cm due

east.

Illustrate the path traveled

by the ant?



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A curious students was






east.

What is the total distance

travelled by the ant?

Resultant Vectors (Graphical Method)


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A curious student was






east.

What is its displacement?

use 1cm=2cm



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The Resultant Vector can

be determined usinggraphical and component

method.

Resultant VectorVector sum of

two or more

vectors



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The Resultant Vector can

be determined usinggraphical and component

method.

Resultant VectorVector sum of

two or more

vectors

Resultant Vectors


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28 July 2012 REDG 2011 67

Resultant Vectors

A flock of birds follows the same

migratory pattern every year. Biologists

noted that they originate from Japan andflies 2500 km 60o S of W to Taiwan for a

stopover. The flock will then turn 400 E of

S and cover a distance of 1500 kmtowards the Batanes Islands in the

Philippines. How far are they from Japan?

Represent the vectors in the problem below and

determine the resultant vector.



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A sailboat is cruising up the Amazon

River. Its sails embraces a 40 km/hr wind

directed at 60o W of N and another windthat is moving at 35 km/hr towards the

West. If the downstream current is

moving at 10 km/hr directed at 20o Eastof South, what is the resultant velocity of

the ship.

Represent the vectors in the problem below and

determine the resultant vector.


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( p )

No matter how you

arrange the vectors aslong as it is head to tail,

you will always get the

resultant vector.


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Most explanation and examples in this presentation are based

of the lesson presentation ofThe Physics Classroom &

Conceptual Physics. The clip arts used were taken from

different sites that I thought are free to use. This is for

classroom use only.

PPTG101213 Scalars and Vectors GALLEGO

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