Position/Velocity/Acceleration Part 1: Definitions Professor Dave Explains English Indonesian

Position/Velocity/Acceleration Part 1: DefinitionsYouTube↗ IA↗(long shot)
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Professor Dave Explains 4.3M subscribers United States YouTube↗

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Indonesian Jihan

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Hey it's professor Dave, let's discuss

Hey, aku Professor Dave.

position, velocity, and acceleration.

Mari kita bahas posisi, kecepatan, dan percepatan.

In physics, we will

often be asking questions like where is

kita akan sering menanyakan pertanyaan seperti

an object, which way is it moving, and how

"Di mana objek itu?", "Ke mana arahnya?",

fast? To discuss the answers to these

dan "Seberapa cepat gerakannya?" Untuk menjawab pertanyaan-pertanyaan tersebut,

questions we will frequently utilize the

kita akan sering menggunakan

concepts of position, velocity, and

konsep posisi, kecepatan, dan percepatan.

acceleration. So before we go any further

Jadi, sebelum kita bahas lebih jauh,

let's define these terms. Position is

mari lihat definisinya terlebih dahulu.

simple, it's just where an object is in

Posisi itu simpel. Posisi adalah letak suatu objek pada suatu tempat.

space. Usually this is discussed with

Biasanya posisi beracuan pada

some kind of reference point or axes in

semacam titik referensi atau sumbu,

mind, and we might express the position

dan kita dapat menyatakan sebuah posisi dari suatu objek

of an object as being some distance from

yang berjarak dengan

this reference point in meters. Velocity

suatu titik dalam satuan meter.

is the change in position over time, so

Kecepatan adalah perubahan posisi relatif terhadap waktu,

if this object travels five meters in

jadi jika suatu objek bergerak sejauh lima meter selama lima detik,

five seconds it is traveling at a velocity of one meter per second. And

objek tersebut bergerak dengan kecepatan 1 meter per detik (1 m/s)

acceleration is the change in velocity

Dan percepatan adalah perubahan kecepatan relatif terhadap waktu.

over time, so if this object starts at a standstill and over five seconds

Jadi jika awalnya benda ini diam, dan selama lima detik selanjutnya

gradually speeds up to 5 meters per

menambah kecepatan secara bertahap sampai 5 m/s,

second, then it is accelerating at one

maka ia mengalami percepatan

meter per second per second, or 1 meter

sebesar 1 meter per detik, per detik,

per second squared. So that's how we

define position, velocity, and

Itulah definisinya.

acceleration. Now let's discuss each of these in more depth. When we talk about

Sekarang, ayo kita bahas lebih dalam.

position we could discuss distance or we could discuss displacement. The

Ketika berbicara tentang posisi, kita bisa membahas 'jarak' dan 'perpindahan'.

difference here is that distance is a

Perbedaannya adalah

scalar while displacement is a vector.

jarak adalah skalar, sedangkan perpindahan adalah vektor.

Let's say you and your friend get dropped off by the school bus at this

Bayangkan kamu dan temanmu turun dari bus di persimpangan ini

intersection and your house is here. Your

dan ini adalah rumahmu.

friend begins to walk down the street

Temanmu mulai berjalan

and up the driveway like a normal person

lewat jalan yang normal.

but you find yourself so overcome with excitement to play video games that you

Tapi kamu sangat semangat untuk bermain game

decide to plow through the yard in a

dan memutuskan untuk memotong jalan lewat pekarangan

straight line to the door.

sampai ke depan pintu.

Your friend has to walk 20 meters down

Temanmu berjalan 20 meter sepanjang jalan

the street and seven meters up the

dan tujuh meter ke jalan masuk

driveway for a total of twenty seven

dengan jarak total 27 meter.

meters, so using the Pythagorean theorem

Jadi, dengan menggunakan teorema Pythagoras,

we find that you only had to walk about 21.2 meters

kita tahu bahwa kamu hanya perlu untuk berjalan sejauh 21,2 meter

and you probably got there a little sooner. What we can say is that you walked different distances, which are

dan mungkin kamu sampai lebih cepat. Dapat kita simpukan bahwa kalian menempuh jarak yang berbeda,

represented by these scalar values, but

yang diwakili oleh nilai skalar ini,

you both had the same displacement

tetapi kalian mempunyai besar perpindahan yang sama

because you ended up in the same spot at the front door. This vector which follows

karena kalian berakhir di tempat yang sama, yaitu di pintu depan.

the straight-line path is the

Vektor garis lurus ini adalah

displacement vector for both of you and

vektor perpindahan kalian berdua,

we can report your position with x and

dan kita bisa menyimbolkan posisi kalian

y-coordinates like this

dengan koordinat x dan y seperti ini

(20, 7) or we could report the

magnitude of the displacement vector

atau kita bisa lihat besar vektor perpindahannya

which will be equal to the shorter distance you traveled and calculate the

yang besarnya sama dengan jarak terpendek yang ditempuh,

angle off the horizontal using trig functions if we desire, in order to

dan menghitung sudutnya menggunakan fungsi trigonometri misalnya,

report the direction of the vector. Next

untuk mengetahui arah vektornya.

let's look at velocity which is the rate

Selanjutnya, mari kita bahas kecepatan

of change in position.

yaitu perubahan posisi.

Most people assume that the words speed and velocity are synonyms and in

Kebanyakan orang berpikir bahwa 'kecepatan' dan 'kelajuan' maknanya sama.

everyday language they are, but the

Di kehidupan sehari-hari memang maknanya sama.

difference in physics is that speed is a

Tapi bedanya di fisika,

scalar and velocity is a vector. If a

kelajuan adalah skalar, dan kecepatan adalah vektor.

group of kids are playing hide-and-seek

Jika sekelompok anak main petak umpet

and they all run away from the seeker in different directions

dan mereka semua lari (dari yang jaga) ke berbagai arah

it is possible that they all run at the

ada kemungkinan bahwa mereka berlari dengan kelajuan yang sama,

same speed because speed only has magnitude and no direction so they could

karena kelajuan hanya mempunyai nilai, tidak punya arah.

all run at a speed of three meters per

Jadi mereka bisa saja berlari dengan kecepatan 3 m/s

second if they are quick little devils

jika mereka bocah-bocah yang lincah.

but each kid would have a unique velocity vector that has a magnitude of

Tetapi setiap anak mempunyai vektor kecepatan masing-masing,

three but also describes the direction

yang bernilai tiga, tetapi juga menjelaskan arah gerakannya

of motion, most likely using the seeker standing still as the point of origin.

dengan tempat jaga sebagai titik asalnya.

Velocity vectors will be extremely

Vektor kecepatan akan menjadi sangat penting nantinya

important as we move forward with

ketika kita membahas kinematika,

kinematics where we will study the motion of objects. In general, average

dimana kita akan membahas pergerakan benda.

speed can be calculated by taking the

Secara umum, kelajuan rata rata dapat dihitung

distance travelled by an object and dividing by the time it took to do so,

dengan membagikan nilai jarak dengan besar waktu yang ditempuh.

so if you walk 85 meters in 46 seconds

Jadi jika kamu berjalan sejauh 85 meter selama 46 detik,

you are walking at an average speed of 1.85 meters per second. To find average

kelajuan rata-ratamu adalah 1,85 m/s.

velocity you can do the same but you

Untuk mencari kecepatan rata-rata, caranya sama,

would have to divide displacement by time.

tetapi kamu harus membagikan 'perpindahan' dengan besar waktunya.

Lastly we have acceleration, which is the

Yang terakhir adalah percepatan,

rate of change in velocity. This is

yaitu perubahan kecepatan.

always a vector,

Percepatan adalah vektor,

because acceleration must occur in a particular direction. If you are in a car

karena percepatan pasti terjadi dengan arah tertentu.

that is standing still and you press on

Jika kamu berada di dalam mobil yang diam

the gas, the car will begin to move

dan kamu menginjak pedal gas,

forward with a fixed acceleration. It

mobil akan bergerak ke depan dengan percepatan tetap.

might accelerate slowly so the vector

Mobilnya bisa saja dipercepat secara perlahan,

may be on the shorter side, but this

sehingga besaran vektornya pendek,

constant acceleration will cause the

tapi percepatan yang tetap ini akan menyebabkan

velocity to increase at a fixed rate,

pertambahan kecepatan dengan harga yang tetap.

let's say an additional meter per second

Katakanlah pertambahannya satu meter per detik per detik,

every second, so over five seconds it

maka setelah lima detik,

will reach a velocity of 5 m/s. Let's say

kecepatannya akan menjadi 5 m/s.

you see a skunk in the middle of the road.

Katakanlah kamu melihat sigung di tengah jalan.

It's your most favorite animal so you

Sigung adalah hewan favoritmu,

slam on the brakes. We can describe this as a deceleration, which is an acceleration in the negative direction.

jadi kamu harus injak rem. Ini adalah 'perlambatan', yaitu percepatan dengan arah sebaliknya (negatif).

Since you are going from a moderate

Karena kamu berubah dari kecepatan sedang ke berhenti

speed to a standstill in a very short

dalam jangka waktu yang singkat,

amount of time this vector will be quite

vektor ini akan menjadi panjang

long and pointing back towards the origin. Now we understand distance and

dan arahnya ke belakang, menuju titik asalnya. Sekarang kita sudah mengerti jarak dan perpindahan,

displacement, speed and velocity, and

kelajuan dan kecepatan,

acceleration, and we can categorize these

dan percepatan,

as being either scalars or vectors.

dan kita bisa membedakan skalar dan vektor.

Before we finish let's look at a moving

Sebelum kita akhiri,

object like this marble rolling to a

mari lihat suatu benda yang bergerak, seperti kelereng yang menggelinding sampai berhenti

stop and visualize all three of these vectors as the object moves. First with

dan visualisasikan ketiga vektor ini ketika bendanya bergerak.

displacement this vector will just elongate as the marble rolls and will

Pertama, perpindahan. Vektornya hanya memanjang ketika kelerengnya menggelinding

span the distance travelled. For velocity

begitu juga jarak yang ditempuh.

the vector will point forward as the

Untuk kecepatan, arah vektornya ke depan (positif)

velocity is positive, since it is moving

karena kelerengnya bergerak ke arah depan,

in the forward direction, and the vector will move along with the marble but it

dan vektornya akan bergerak bersama kelerengnya,

will decrease in magnitude as the marble

tetapi nilainya akan terus berkurang seiring melambatnya kelereng,

slows down until eventually disappearing

sampai akhirnya menghilang

when the marble comes to a rest, where it has zero velocity. And then for

ketika kelerengnya berhenti dan kecepatannya nol.

acceleration the vector points in the

Untuk percepatan, vektornya mengarah ke arah negatif

negative direction since velocity is

karena kecepatannya berkurang,

decreasing or becoming smaller per unit

dan semakin kecil seiring berjalannya waktu,

time but it will be constant in

Tetapi besarnya akan tetap sama

magnitude since this is a constant

karena ini adalah perlambatan konstan,

deceleration due to friction from the surface it's rolling on. We can view all

yang disebabkan oleh gesekan dengan permukaan.

three of these at once just to drive things home. Make sure you understand the magnitude and direction of each of these vectors at each moment in time.

Kita bisa melihat tiga hal ini sekaligus. Pastikan kamu sudah mengerti tentang besar dan arah masing-masing vektor ini.

Let's check comprehension.

Coba tes pemahamanmu. Di mobil, dari keadaan berhenti, kamu mulai mempercepat ke arah depan. Ketika kamu mencapai kecepatan maksimum, kamu memperlambat hingga berhenti. Lalu kamu memutar balik mobil dan kembali ke titik awal dengan cara yang sama seperti kamu datang tadi. Untuk setiap bagian, tentukan apakah setiap vektor (perpindahan, kecepatan, percepatan) menuju ke arah depan atau belakang, dan apakah besarnya bertambah, berkurang, atau tetap. a) percepatan awal b) perlambatan awal c) percepatan balik d) perlambatan balik a) Perpindahan: Ke depan/bertambah Kecepatan: Ke depan/bertambah Percepatan: Ke depan/tetap

b) Perpindahan: Ke depan/bertambah Kecepatan: Ke depan/berkurang Percepatan: Ke belakang/tetap c) Perpindahan: Ke depan/berkurang Kecepatan: Ke belakang/bertambah Percepatan: Ke belakang/tetap d) Perpindahan: Ke depan/berkurang Kecepatan: Ke belakang/berkurang Percepatan: Ke depan/tetap

Thanks for watching, guys. Subscribe to my

Terima kasih sudah menonton.

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as always, feel free to email me:

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