Tyas - Motion

8/8/2019 Tyas - Motion

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MotionotionGrade VIII Semester 1

2010/2011

Tyas Ajeng Puspitasari, S.Pd

Junior High School 1 Malang

www.tyas-physics.blogspot.com


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What is motion? What is relative motion? What is difference between distance

and displacement?

What is speed? What is the difference between speedand velocity?

What is acceleration?

How can we use graph to describe

motion?



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What comes to your mind when you hearthe word motion?

,In physics motionis a change inlocation or position of an object

with respect to time

The moving object is identified byits change position from a point of

reference

Motion is always observed andmeasured relativeto a frame of.reference



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Distance and DisplacementDistance and Displacement

q Distanceis the otal pathravelled by the bodywithout considering thedirection .of its motion

qq Displacementis the change

of position of body from,the initial point or hehortest distance fromne point to another .

qq The SI unit of distance and

displacement is the meter[ ].m



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B

Distance VsDisplacement

Displacement

5

200 m

250 m

150 m

distance =

displacement =

A

150 m + 250 m = 400 m

200 m

A

C



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Problems of distance and DisplacementProblems of distance and Displacement

A100 m

100 m

100 mB

.1 ) ,a In Figure beside what is the distance t)b What is the displacement of the car?

, , ,walks 4 meters East 2 meters South 4 meters West and fin

?



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SpeedSpeed

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t = 1 s10 m

t = 1 s10 m

t = 1 s10 m

q The peed of an object is defined as the distancetravelled by the object per unit timeq The speed of a body tells us how quickly or slowly a body ismovingq ( / ).Speed is measured in the SI unit of meter per second m s

Another ( / )commonly unit is kilometer per hour km hour and mileper hour ( )mph


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verage Speed and Instantaneousspeed


For most journeys, speed is not constant.

Instantaneous Speed - the speed at anygiven instant in time. This is measuredusing a speedometer

Average Speed - the average of allinstantaneous speeds.

Speed isscalar quantity, has only( ).numerical value magnitude

A car speedometer


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Velocity

elocity is distance travelled per unit time ina stated direction

Velocity is speed in a specific direction The SI unit for velocity is meter per second

( / ). /m s Other commonly unit is kilometer hour( / )km hour

Velocity isvector quantity, has a direction and( ).a numerical value magnitude



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roblems of Speed and Velocity


,we drive at this average speed for 5 hours how far will we go?.ting source was 3 3 km ,away from where you were standing how lonin 44 s

, ,h stopped for 15 min then traveled 100 km to the west for 45 m


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AccelerationAcceleration

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cceleration is defined as the rate of changeof velocity

,Where

= ( /a acceleration m s2) = ( / )v change in velocity m svt = ( / )final velocity m sV0

= ( / )initial velocity m s=t time taken for the change

( )s

q .Acceleration has a direction and magnitudeq /The SI unit for acceleration is m s2q ,Acceleration can be positive negative or zer



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AccelerationAcceleration

6 m/s4 m/s0 m/s 2 m/s

Velocity goes up by 2 meters per second every seco

1 s 2 s 3 s 4 s

12 www.tyas-physics.blogspot.com


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ositive and negativeaccelerationq Positive acceleration ( = +)a The direction of the acceleration is in the same

direction as the velocity since the speed is increasing.

q /Negative acceleration deceleration ( =-)a The direction of the acceleration is in the opposite

direction to the direction of the velocity since the speed is

decreasing



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niform Linear Motion (gerak lurusberaturan)

Motion of a body in straight linewith a constant velocity v --->is constant =v 0 a = 0



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niformly Accelerated Motion (GerakLurus Berubah Beraturan)

Motion of a body if its accelerationremains constant throughout its.motion

v is changes

a = constant



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ormula for Uniformlyccelerated Motion

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atvvt += 0

2

0

2

1attvs +=

asvvt

22

0

2

+= :Notevt = final velocity

( / )m sv0= initial velocity

( / )m s= ( /a acceleration m s2)

s = ( )displacement m= ( )t time s

t

vva t 0

=



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roblems of Uniform AcceleratedMotion1. A car increases its velocity steadily from 72 km/h to 108 km/h in 5 s. What

is its acceleration in m/s2?

2. An object moves with initial velocity of 4 m/s then it is accelerated withacceleration of 3 m/s2 for 5 seconds. What is final velocity of theobject?

3. A car is accelerated at 6 m.s-2 from an initial velocity of 2 m.s-1 for 10seconds. What is the final velocity and the distance moved?

4. An object moves from rest with a uniform acceleration of 2 m/s2. What isthe velocity of the object after 30s?

5. Andri drive a motorcycle with initial velocity of 20 m/s. When hes near to

his house, he brake his motorcycle for 5 seconds until the motorcyclestop in front of his house precisely. What is the deceleration of Andrismotorcycle?

6.



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Distanceinm

eter

Time in Seconds0 1 2 3 4 5 6 7 8 9

40

120

160

200

80

( )RAPH Distance vs Time

18

THE SLOPE = AVERAGE SPEED

Distance (m) Vs. Time (sec.)

x

y

Run

RiseSlope

=

=

Time

DistanceSpeed =

Rise

Run

Y

X

smspeedaverage 204

80

37

60140==

=www.tyas-physics.blogspot.com


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.raph distance vs timeObject at rest(v=0)

Uniform Linear Motion(v= constant; a =0 )

Uniformly Accelerated Motion(v is changed; a = constant)



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( )RAPH Speed vs Time


. =r a speed vs time graph the distan

,vs time graph is 40 cm thus total distanc


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.raph speed vs timeUniform Linear Motion(v= constant; a =0 )

Uniformly AcceleratedMotion(v is changed; a = +)

Uniformly DeceleratedMotion(v is changed; a = -)



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roblems of graph of Motion


.1 - .The distance time graph of a moving object is shown below.a What is the

velocityof

objectduring

timeinterval

-0s 3s?.b What is the

velocityof

object

for thenext 3s?.a.b

.3 - .The speed time graph of an object moving in a straight line is shown below

.a Calculateits


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roblems of graph of Motion


:is shown below Calculate.a Its acceleration during the first 5 seconds.b Its deceleration during the last 2 seconds.c The total distance travelled

.d The average speed of the object for the whole journey.

.a What is the total distance of the car

.b ( : What is the total displacement of the car? NOTE The negative area shown the d


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Reference

Glencoe Science. 2005. Motion, Forces and Energy. USA: The McGraw-HillCompanies, Inc.

A Glencoe Program. 2005. Physics Principles and Problems. USA: The McGraw-Hill companies, Inc.

Yap Eng Keat & Khoo Koh Kow. 2008. Longman Essential Physics Form 4(Bilingual Text). Selangor: Pearson Malaysia Sdn.Bhd.

Low Kia Keat & Julie Quah. 2006. Physics Expression N Level Science.Singapore: Panpac Education

Loo Kwok Wai & Loo Wan Yong. 2007.Science in Focus Physics N Level.Singapore: Pearson Education South Asia Pte. Ltd.

http://en.wikipedia.org/wiki/Motion_(physics)


Tyas - Motion

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