MAPEL FISIKA Gerak Harmonik

 Getaran Harmonik : Pengertian, Syarat, Dan Rumus Beserta Contoh Soalnya Secara Lengkap

Pengertian Getaran Harmonik

Gerak harmonik merupakan gerak sebuah benda dimana grafik posisi partikel sebagai fungsi waktu berupa sinus (bisa dinyatakan dalam bentuk sinus atau kosinus). Gerak semacam ini disebut dengan gerak osilasi atau getaran harmonik.

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Contoh getaran harmonik

1. dawai pada alat musik
2. gelombang radio
3. arus listrik AC
4. denyut jantung.
5. Galileo di duga sudah memakai denyut jantungnya untuk pengukuran waktu dalam pengamatan gerak.

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Syarat Getaran Harmonik

Syarat suatu gerak dikatakan getaran harmonik, yaitu antara lain :

1. Gerakannya periodik (bolak-balik).
2. Gerakannya selalu melewati posisi keseimbangan.
3. Percepatan atau gaya yang bekerja pada benda sebanding dengan posisi/simpangan benda.
4. Arah percepatan atau gaya yang bekerja pada suatu benda selalu mengarah ke posisi keseimbangan.

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Periode dan Frekuensi Getaran Harmonik

a. Periode dan Frekuensi Sistem Pegas

Pada dasarnya, gerak harmonik adalah suatu gerak melingkar beraturan pada salah satu sumbu utama. Oleh sebab itu, periode dan frekuensi pada pegas bisa dihitung dengan menyamakan antara gaya pemulih (F = -kX) dan gaya sentripetal (F = -4π 2 mf2X).

Periode dan frekuensi sebuah sistem beban pegas hanya bergantung pada massa dan konstanta gaya pegas.

b. Periode dan Frekuensi Bandul Sederhana

Sebuah bandul sederhana terdiri atas sebuah beban bermassa m yang digantung di ujung tali ringan (massanya dapat diabaikan) yang panjangnya l. Bila beban ditarik ke satu sisi dan dilepaskan, maka beban berayun melalui titik keseimbangan menuju ke sisi yang lain.

Bila amplitudo ayunan kecil, maka bandul melakukan getaran harmonik. Periode dan frekuensi getaran pada bandul sederhana sama seperti pada pegas. Artinya, periode dan frekuensinya dapat dihitung dengan menyamakan gaya pemulih dan gaya sentripetal.

Gaya Yang Bekerja Pada Bandul Sederhana

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Persamaan gaya pemulih pada bandul sederhana adalah F = -mg sinθ . Untuk sudut θ kecil (θ dalam satuan radian), maka sin θ = θ . Oleh karena itu persamaannya dapat ditulis F = -mg (X/l). Karena persamaan gaya sentripetal adalah F = -4π 2 mf2X, maka kita peroleh persamaan sebagai berikut.

Periode dan frekuensi bandul sederhana tidak bergantung pada massa dan simpangan bandul, tetapi hanya bergantung pada panjang tali dan percepatan gravitasi setempat.

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Contoh Soal Getaran Harmonik

Suatu benda bergetar hingga membentuk suatu gerak harmonis dengan persamaan

y = 0,04 sin 20π t

dengan y adalah simpangan dalam satuan meter, t yaitu waktu dalam satuan sekon. Tentukan beberapa besaran dari persamaan getaran harmonis tersebut:
a) amplitudo
b) frekuensi
c) periode
d) simpangan maksimum
e) simpangan saat t = 1/60 sekon
f) simpangan saat sudut fasenya 45°
g) sudut fase saat simpangannya 0,02 meter

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Pembahasan
Pola persamaan simpangan gerak harmonik diatas ialah

y = A sin ωt
ω = 2π f

atau

ω = 2π/T

a) amplitudo atau A
y = 0,04 sin 20π t
↓
A = 0,04 meter

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b) frekuensi atau f
y = 0,04 sin 20π t
↓
ω = 20π

2πf = 20π
f = 10 Hz

c) periode atau T
T = 1/f
T = 1/10 = 0,1 s

d) simpangan maksimum atau ymaks

y = A sin ωt
y = ymaks sin ωt

y = 0,04 sin 20π t
↓
y = ymaks sin ωt

ymaks = 0,04 m

(Simpangan maksimum tidak lain adalah amplitudo)

e) simpangan saat t = 1/60 sekon

y = 0,04 sin 20π t
y = 0,04 sin 20π (1/60)
y = 0,04 sin 1/3 π
y = 0,04 sin 60° = 0,04 × 1/2√3 = 0,02 √3 m

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f) simpangan saat sudut fasenya 45°

y = A sin ωt
y = A sin θ

dimana θ adalah sudut fase, θ = ωt

y = 0,04 sin θ
y = 0,04 sin 45° = 0,04 (0,5√2) = 0,02√2 m

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g) sudut fase saat simpangannya 0,02 meter
y = 0,04 sin 20π t
y = 0,04 sin θ
0,02 = 0,04 sin θ
sin θ = 1/2
θ = 30°

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Itulah ulasan tentang Getaran Harmonik : Pengertian, Syarat, Dan Rumus Beserta Contoh Soalnya Secara Lengkap Semoga apa yang diulas diatas bermanfaat bagi pembaca. Sekian dan terimakasih.

MAPEL ENGLISH LM BAB 9 Proverb and riddle

 

PROVERBS AND RIDDLE

PROVERBS AND RIDDLE

OBJECTIVES OF THE STUDY

Students are expected able to know, understand, and use proverbs in their spoken and written communication.

LEARN ABOUT IT!

Dr. Bougher knows a lot about the forest. In the clip, he spent a lot of time describing where things are.

On our left here, we have a very good example of the jarrah forest, the famous jarrah forest of Western Australia.

And on our right here, we have the contrast, which is the mined area, and on this area we can see that rehabilitation has occurred about three years ago.  This is world’s best practice.

Our jarrah forest is our reference point, it’s our library of information, this is our baseline, this is what we had before we mined.  I think some of the outward signs are showing us that it’s quite healthy.

The proof in the pudding is not you and I sitting here today, but the proof of the pudding might be in ten year’s time, twenty year’s time – whether this forest is flourishing for our children and grandchildren.

So far so good.

The speaker said “The proof in the pudding” it is a proverb. Proverbs usually use in informal language. Its are not obvious meaning, we can understand by memorizing them.

The proof in the pudding. Pudding is kind of food, we know its delicious or not by tasted them.  So “The proof in the pudding” It’s means that you can only judge the quality of something after it has been tested or

experienced over time.

What are proverbs?

Proverbs is a collection of wise sayings that offer advice about how to live your life. In line with this definition, according to www. pelajarelit.blogspot.com, proverbs are a verse or collection of words having a fixed arrangement containing certain definitions and gives positive suggestions. 

How can you use proverbs to learn English?

It's good to know the really common English proverbs because you hear them come up in conversation all the time. Sometimes people say the entire proverb to give advice to a friend. More often, someone will say just part of a proverb like this:

You know what they say: when the going gets tough...

SOCIAL FUNCTIONS OF PROVERB

• Proverb have a function to teaching, enlightening, and persuading people. Proverbs play many roles in society. The most common role is to educate on what might happen if they do something. A proverb contains wisdom, truth, morals, and traditional views.
• Proverb has been and remains a most powerful and effective instrument for the transmission of culture, social morality, manner, and ideas of a people from one generation to another. The proverbs deal with knowledge, experience, hard work, and human relations.
• Proverb and proverbial sayings have for centuries been equally popular with all nations, despite their regional diversities, and clearly, for the impact the have made.
• Proverb can be used to tech people, give them some advice, help in difficult situations, show people what the most important thins in life, and show the proper way in life.
• Proverbs are very often used in personal interaction.
• Proverb can also be used mock someone or criticize.

STRUCTURE OF PROVERBS

Proverbs often from clusters that share a common structure.
– Opposite parallel
– Similiar parallel
– Single statement
– Statement with an explanation
– Comparison
– Descriptive list
– Use of clause or instruction

LANGUAGE FEATURE OF PROVERBS

Proverbs use figurative language, we have analyzed what is the literal meaning in it.

SOME EXAMPLE OF PROVERBS

The most important English Proverbs

This is a list of some of the most important and well-known English proverbs. Below each one, there's a simple explanation.

The meanings of some of these phrases have shifted over the years so a proverb might have originally had a different meaning than the one I explain.

a different meaning than the one I explain.

1.         "TWO WRONGS DON'T MAKE A RIGHT." WHEN SOMEONE HAS DONE SOMETHING BAD TO YOU, TRYING TO GET REVENGE WILL ONLY MAKE THINGS WORSE.

2.         "The pen is mightier than the sword." Trying to convince people with ideas and words is more effective than trying to force people to do what you want.

3.         "When in Rome, do as the Romans." Act the way that the people around you are acting. This phrase might come in handy when you're traveling abroad notice that people do things differently than you're used to.

4.         "The squeaky wheel gets the grease." You can get better service if you complain about something. If you wait patiently, no one's going to help you.

5.         "When the going gets tough, the tough get going." Strong people don't give up when they come across challenges. They just work harder.

6.         "No man is an island." You can't live completely independently. Everyone needs help from other people.

7.         "Fortune favors the bold." People who bravely go after what they want are more successful than people who try to live safely.

8.         "People who live in glass houses should not throw stones." Don't criticize other people if you're not perfect yourself.

9.         "Hope for the best, but prepare for the worst." Bad things might happen, so be prepared.

10.      "Better late than never." It's best to do something on time. But if you can't do it on time, do it late.

11.      "Birds of a feather flock together." People like to spend time with others who are similar to them.

12.      "Keep your friends close and your enemies closer." If you have an enemy, pretend to be friends with them instead of openly fighting with them. That way you can watch them carefully and figure out what they're planning.

13.      "A picture is worth a thousand words." Pictures convey emotions and messages better than written or spoken explanations. That's why Phrase-Mix has illustrations :)

14.      "There's no such thing as a free lunch." Things that are offered for free always have a hidden cost.

15.      "There's no place like home." Your own home is the most comfortable place to be.

16.      "Discretion is the greater part of valor." Sometimes it's important to know when to give up and run away, instead of always acting brave and maybe getting hurt.

17.      "The early bird catches the worm." You should wake up and start work early if you want to succeed.

18.      "Never look a gift horse in the mouth." If someone offers you a gift, don't question it.

19.      "You can't make an omelet without breaking a few eggs." When you try to do something great, you'll probably make a few people annoyed or angry. Don't worry about those people; just focus on the good results.

20.      "God helps those who help themselves." Don't just wait for good things to happen to you. Work hard to achieve your goals.

21.      "You can't always get what you want." Don't whine and complain if you don't get what you wanted.

22.      "Cleanliness is next to godliness." Be clean. God likes that.

23.      "A watched pot never boils." If something takes time to finish, don't watch it too closely because it will seem like it's taking forever.

24.      "Beggars can't be choosers." If you're asking for a favor from someone else, you have to take whatever they give you.

RIDDLE

A riddle is a type of poetry that describes something without actually naming what it is, leaving the reader to guess. It is a light hearted type of poetry which involves the reader. Riddles can be about anything, from riddles about animals to riddle about objects. There are no rules on how to structure a riddle poem, a riddle can be funny or it can rhyme, it depends on the person writing the riddle.

EXAMPLE :

1. It’s an animal. It’s an orange black. It has stripes. It has four paws. It lives in the jungle. What is it? It is a tiger.
2. I have three eyes, all in a row. When the red one opens, all freeze. I am traffic light.
3. Example of Rhyming Riddle
I come in different style.
I can help you walk for miles.
Come in pair
I’m something what you wear
With heels I’m glam
Can you guest what I am?
I am a shoes.

SOCIAL FUNCTION OF RIDDLE

A riddle is a statement, question, or phrase that has a double meaning. It is an amusing game for children and adults. Today riddle aren’t used as much as they were in ancient times, but they remain a definite way to get your mind working.

• When someone uses a riddle, it can be a thought provoking challenge to figure it out on your own, or it can be a funny comment that makes you laugh. Riddles can be great brain busters or conversation starters to get you think. Riddle games have been played since times, and are still being played today.
• Riddles have significant roles. They include roles that may be described as cultural, educative, intellectual, ideological, cosmological, and political. Riddles teach logic about the social and cultural environment, social norms, history, biology, and much more.
• Riddles can help in memory training for children as they are expected and encourage to remember the correct answers to the riddles. Riddles also can help to introduce a variety of vocabulary. They also provide opportunities to play phonetic, morphological, grammatical, and semantic games as they exhibit a variety of linguistic expressions and structures.

In conclusion, riddles have a role in the education of communities and in the development of analytical thinking lies the fact that the answer to the riddle is already known to the audience.

STRUCTURE OF RIDDLE

Riddle have no form set. Riddles can be a question with a quick witty answer. They can be just a sentence that makes you have a sudden realization. We can also create riddles from words that rhythm with a word in a riddle’s answer, other word and phrases that use the funny part of an answer.

CHARACTERISTIC OF RIDDLE

A riddle is a verbal puzzle, an enigmatic statement, description, or question posed by one person to another, or to a group, who have to guess the answer. We use the term loosely for more than one kind of puzzle. However, the riddle proper relies on imagery for its effects; often quite poetic imagery. Some riddles use pronoun “i” even though the word that should be guessed is a thing. For example : “If you have me, you won’t to share me. If you share me, you haven’t got me. What am i?” The answer is “a secret”.

KEY POINTS

Learning proverbs can also help you to understand the way that people in English-speaking cultures think about the world.

Proverbs can also give you good example sentences that you can memorize and use as models for building your own sentences.

Proverbs usually use in informal language. Its are not obvious meaning, we can understand by memorizing them.

A riddle is a type of poetry that describes something which needs to be guessed by other people. It can be anything that involves readers. Riddle does not have a specific structure. It can be in the form of statements, questions, or phrases, and it can rhyme. A riddle can be funny and challenging.

MAPEL KIMIA BAB 7 Tata nama senyawa kimia

 

TATA NAMA SENYAWA BINER

1.         RUMUS KIMIA

Rumus kimia merupakan kumpulan lambang atom dengan aturan tertentu. Misalnya, rumus air adalah H₂O dan garam dapur (natrium klorida) adalah NaCl. Jumlah tiap atom pada rumus kimia ditulis sebagai angka indeks. Pada rumus kimia air (H₂O), angka indeks H adalah 2 dan angka indeks O adalah 1 (angka indeks I tidak perlu ditulis). Adapun pada rumus kimia garam dapur (NaCI), angka indeks kedua atom adalah 1 sehingga tidak perlu ditulis. Rumus kimia suatu zat adalah khas. Kekhasan itu ditentukan oleh daya ikat dan bilangan oksidasi yang dimiliki suatu atom.

1. a.        Daya Ikat Atom

Daya ikat atom adalah kemampuan suatu atom untuk mengikat atom lain sehingga membentuk suatu molekul. Daya ikat atom juga disebut valensi. Tiap atom mempunyai daya ikat tertentu.

Untuk memahami daya ikat atom, perhatikan senyawa HCI, H₂O, NH₃, SO₂, SO₃, dan CH. Ternyata, Cl mengikat 1 atom H, O mengikat 2 atom H, N mengikat 3 atom H, S mengikat 2 atau 3 atom O, dan C mengikat 4 atom H. Karena mempunyai daya ikat paling kecil, atom H dijadikan pembanding dan ditetapkan memiliki valensi 1. Oleh karena itu, valensi atom CI adalah 1, valensi atom O adalah 2, valensi atom N adalah 3, valensi atom S adalah 4 atau 6, dan valensi atom C adalah 4.

b.        Tata Nama Senyawa Biner

Senyawa biner adalah kimia yang hanya terbentuk dari dua unsur. Unsur yang terbentuk tersebut dapat terdiri atas unsur logam dan bukan logam atau keduanya terdiri atas unsur bukan loga

Jika senyawa biner terdiri atas unsur logam dan bukan logam, aturan penamaan senyawanya sebagai berikut.

Nama unsur logam disebutkan lebih dahulu, kemudian diikuti nama unsur bukan logam yang diakhiri dengan akhiran –ida.

Contoh :

NaCl = Natrium klorida         MgBr₂=Magnesium bromida

Na adalah unsur logam       Mg adalah unsur logam

Cl adalah unsur non logam         Br adalah unsur non logam

Senyawa ionik walaupun tersusun atas ion positif dan negatif, tetapi secara keseluruhan bersifat netral, sehingga muatan totalnya adalah nol. Ini berarti satu Na⁺ akan bergabung dengan satu Cl^– dalam NaCl dan satu Mg²⁺ bergabung dengan dua Br^– dalam MgBr₂ demikian seterusnya. Berikut ini contoh pemberian nama dan simbol senyawa sederhana :

SENYAWA	NAMA SENYAWA	SENYAWA	NAMA SENYAWA
Li2O	Litium oksida	CaO	Kalsium oksida
NaBr	Natrium bromida	SrO	Stronsium oksida
KCl	Kalium klorida	BaCl2	Barium klorida
Rb2O	Rubidium oksida	Al2O3	Aluminium oksida
CsI	Cesium iodida	ZnO	Seng oksida
MgCl	Magnesium klorida	AgCl	Perak klorida

1. 2.         Jika senyawa biner terdiri atas unsur bukan logam dan bukan logam, aturan penamaan senyawanya sebagai berikut.

Nama unsur bukan logam yang kelelektronegatifannya lebih rendah disebutkan lebih dahulu, kemudian diikuti nama unsur bukan logam yang lain dan diakhiri dengan akhiran –ida. Senyawa yang terbentuk antara unsur bukan logam dan bukan logam merupakan senyawa yang berikatan kovalen. Jumlah atom yang dimiliki oleh senyawa biner disebutkan dengan cara memberi awalan bahasa Latin sebagai berikut :

1     =     mono           6     =   heksa

2     =     di                  7     =   hepta

3     =     tri                  8     =   okta

4     =     tetra              9     =   nona

5     =     penta           10   =   deka

Awalan bahasa Latin mono tidak diletakkan pada nama unsur non logam yang pertama melainkan pada unsur nonlogam kedua. Awalan bahasa latin dari nama logam pertama disebutkan mulai dari yang berjumlah 2, dst. Contoh :

N₂O         =     dinitrogen monoksida

NO           =     nitrogen monoksida

N₂O₃        =     dinitrogen trioksida

NO₂         =     nitrogen dioksida

N₂O₅        =     dinitrogen pentaoksida

CCl₄        =     karbon tetraklorida

CO           =     karbon monoksida

CO₂         =     karbon dioksida

Unsur-unsur logam dengan bilangan oksidasi lebih dari satu jenis, maka bilangan oksidasinya ditulis dengan angka romawi

Sebelumnya harus dipahami pengertian dan cara menentukan bilangan oksidasi. Bilangan oksidasi menyatakan jumlah elektron yang terlibat pembentukan ikatan.

Jika melepaskan elektron, suatu atom memiIiki bilangan oksidasi positif. Sebaliknya, jika menangkap elektron, suatu atom memiliki bilangan oksidasi negatif. Pengertian bilangan oksidasi seperti itu berlaku untuk molekul ionik. Jika demikian, bagaimana bilangan oksidasi untuk molekul kovalen?

Molekul kovalen dibedakan atas molekul kovalen polar dan nonpolar. Untuk molekul kovalen polar, atom yang lebih elektronegatif dianggap bermuatan negatif dan molekul yang lain dianggap bermuatan positif. Adapun untuk molekul kovalen nonpolar, bilangan oksidasinya sama dengan nol.

Aturan bilangan oksidasi (biloks) adalah sebagai berikut :

1. Bilangan oksidasi unsur bebas (monoatomik, diatomik, atau poliatomik) sama dengan 0 (nol). Misalnya : bilangan oksidasi Na, Mg, Fe, O, Cl₂, H₂, P₄ dan S₈ = 0
2. Bilangan oksidasi unsur H dalam senyawa = +1, kecuali pada senyawa hidrida =  –1 (misalnya : NaH)
3. Bilangan oksidasi unsur O dalam senywa = –2, kecuali pada senyawa peroksida = –1  (misalnya : Na₂O₂, H₂O₂, BaO₂), dan pada senyawa oksifluorida (OF₂) = +2
4. Bilangan oksidasi unsur logam dalam senyawa selalu positif dan nilainya sama dengan valensi logam tersebut. ( Misalnya : Biloks logam gol.IA= +1, gol.IIA=+2, gol.IIIA=+3)
5. Bilangan oksidasi unsur golongan VIIA dalam senyawa = –1
6. Bilangan oksidasi unsur dalam bentuk ion tunggal sama dengan muatannya. (Misalnya Biloks Na pada Na⁺= +1, Cl pada Cl^–=–1, Mg pada Mg²⁺=+2)
7. Jumlah bilangan oksidasi unsur-unsur dalam suatu senyawa sama dengan 0 (nol), Misalnya :

Biloks S pada H₂SO₄ ditentukan dengan cara :

H₂SO₄     =     0

( 2 x biloks H) + S + (4 x biloks O)     =     0

( 2 X 1) + S + (4 X (-2) )     =     0

2 + S – 8     =     0

S     =     8 – 2

S     =     +6

1. Jumlah bilangan oksidasi unsur-unsur dalam suatu ion poliatom sama dengan muatannya.

Misalnya :

Biloks Cr pada Cr₂O₇^2-

Cr₂O₇^2-     =   –2

Cr₂ + ( 7 x biloks O )     =   –2

Cr₂ + ( 7 x (-2) )     =   –2

Cr₂ – 14     =   –2

Cr₂     =   14 – 2

Cr     =   12 / 2

Cr     =   +6

Contoh 1.

Senyawa CrO diberi nama dengan aturan sebagai berikut :

1. Mencari biloks Cr pada CrO, dengan cara :

CrO  =     0

Cr + (1 x biloks O)  =     0

Cr + ( 1 x (-2))  =     0

Cr + (-2)  =     0

Cr – 2  =     0

Cr  =     2

Maka biloks Cr pada CrO  =     2

1. Biloks Cr ditulis dengan angka Romawi setelah nama logam dalam bahasa Indonesia, dilanjutkan nama nonlogam dan diakhiri dengan akhiran –ida. Sehingga nama senyawa CrO adalah Kromium (II) oksida

Contoh 2.

Senyawa FeF₃ diberi nama dengan aturan sebagai berikut :

1. Mencari biloks Fe pada FeF₃, dengan cara :

FeF₃  =     0

Fe + (3 x biloks F)  =     0

Fe + ( 3 x (-1))  =     0

Fe + (-3)  =     0

Fe – 3  =     0

Fe  =     3

Maka biloks Fe pada FeF₃  =     3

1. Biloks Fe ditulis dengan angka Romawi setelah nama logam dalam bahasa Indonesia, dilanjutkan nama nonlogam dan diakhiri dengan akhiran –ida. Sehingga nama senyawa FeF₃ adalah Besi (III) florida