LK siswa kelas 11 IPA keseimbangan n dinamika rotasi

LEMBAR KERJA SISWA

BAB 1.  KESEIMBANGAN DAN DINAMIKA ROTASI

NAMA :.............................................

KELAS    : ............................................

Kerjakan soal-soal di bawah ini dengan benar!!!

1. Sebuah roda dengan garis tengah 540 mm sedang berputar pada 1500/p rpm (rotasi per menit) hitunglah :

(a) kecepatan sudut roda ( dlm rad/s) dan

(b) kecepatan linier sebuah titik pada tepi roda (dlm m/s).

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2. Sebuah partikel P bergerak dalam suatu bidang pada waktu t, vektor radius OP telah berputar melalui sudut q rad, dimana           q = 5t – t² , t dalam sekon. Hitunglah :

a.     kecepatan sudut pada saat t.

b.     kapan kecepatan sudut bernilai nol?

c.     Tunjukkan bahwa percepatan sudut partikel adalah tetap.

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3. Sebuah roda berputar dengan poros sumbu z dengan percepatan sudutnya dinyatakan oleh a = (1,86 rad / s²)t, dengan t dalam sekon tentukan

a.    kecepatan sudut pada t = 2s, jika kecepatan sudut awal adalah –2,9 rad/s

b.    sudut yang ditempuh roda setelah berputar selama 2,0 s.

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4. Kecepatan putar sebuah poros bertambah secara tetap dari 1 rad/s menjadi 5 rad/s dalam waktu 0,8 s. jika diameter poros adalah 80 mm, tentukan percepatan total yang dialami poros.

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5. Poros sebuah motor listrik yang mula-mula diam mengalami percepatan tetap 15 rad /s² selama 0,4 s.  tentukan sudut yang ditempuh poros

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6. Sebuah roda dipercepat secara tetap 2 rad/s² sampai berputar pada kecepatan1500/p rpm.  Jika roda menempuh 25/p putaran selama waktu dipercepat tersebut, tentukan kecepatan sudut awal ( dalam rad/s)

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7. Diketahui momen gaya t suatu benda adalah 20 Nm, dan gaya yang digunakan adalah 5 N jika gaya tersebut tegak lurus terhadap lengan, maka berapakah besar lengan momen gaya tersebut?

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8. pada empat persegi panjang berukuran       8 m x 6 m  bekerja gaya – gaya F1 sampai F6 seperti pada gambar, Tentukan momen yang dihasilkan tiap gaya berikut momen totalnya terhadap poros melalui titik O dan titik A

 

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9. Sebuah gaya F = (120)i + (180)j dikerjakan pada suatu benda pada suatu titik yang memiliki vektor kedudukan r = (3m)i – (2m)j terhadap acuan O.  hitunglah momen yang dikerjakan gaya ini terhadap O.

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10.    Sebuah gaya F = (120 N)i + (150 N)j – (100 N)k dikerjakan pada suatu benda pada suatu titik yang memiliki vektor r = (1,4)i + (2,1) j terhadap acuan O.  hitunglah momen yang dikerjakan gaya ini terhadap O.

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11.    Sebuah roda mula-mula dalam keadaan diam setelah berputar selama 10 s, kecepatan angulernya menjadi 8 rad/s maka percepatan yang dialaminya adalah

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12.    Sebuah piringan memiliki jari-jari 10 cm.  Roda tersebut berotasi dengan kecepatan anguler 20 rad/s. tentukan kecepetan linier dari

a.    sebuah titik yang berada pada pinggir piringan

b.    sebuah titik yang berada 5 cm dari pusat piringan

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