ULANGAN TENGAH SEMESTER(UTAMA)

MATA PELAJARAN : FISIKAKELAS / PROGRAM : XI MIANama:Kelas/No:Nilai:

HARI / TANGGAL : Selasa/7 Oktober 2014WAKTU : 90 menit (12.00 13.30)

1. Sebuah partikel sedang bergerak pada suatu bidang dengan sumbu koordinat x dan y. Posisi partikel berubah terhadap waktu mengikuti persamaan r = (6 + 3t)i + (8 + 4t)j dengan r dalam meter dan t dalam sekon. Tentukanlah:a. perpindahan partikel dalam selang waktu t = 0 hingga t = 2 sekon;b. besar kecepatan rata-rata partikel dalam selang waktu t = 0 hingga t = 2 sekon;c. besar dan arah kecepatan partikel pada saat t = 2 sekon.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________2. Sebuah benda bergerak dengan kecepatan awal 3 m/s. Jika benda mengalamipercepatan a (t) = (4t 2) m/s2, tentukanlah:a. persamaan kecepatan benda, danb. kecepatan benda pada t = 2 sekon.________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________3. Dari titik A di tanah, sebuah bola dilemparkan dengan kecepatan awal 20 m/s dan sudut elevasi 37 (sin 37 = 0,6). Jika g = 10 m/s2, hitunglah:a. komponen kecepatan awal dalam arah horizontal dan vertikal (V0x dan V0y).b. kecepatan bola setelah 0,4 sekon,c. posisi bola setelah 0,4 sekon,___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________4. Sebuah benda dilemparkan dari puncak sebuah gedung yang tingginya 40 m.Kecepatan awal benda 20 m/s dengan sudut elevasi 30. Tentukana. Waktu yang diperlukan benda dari titik A ke titik B (lihat Gambar)b. jarak terjauh dalam arah mendatar yang dapat dicapai benda, dihitung dari dasar gedung (X=?).____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________5. Sebuah benda mula-mula diam, kemudian berotasi dengan persamaan percepatan sudut . Tentukan:a. kecepatan sudut pada saat t = 2 s (jika kecepatan awal sudut 0 rad/s),b. persamaan posisi sudut benda jika saat t = 2 s posisi sudutnya = 2 rad! ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________6. Dua benda A dan B masing maing massanya 4 kg dan 9 kg diletakkan terpisah pada jarak 50 cm. Tentukan:a. gaya gravitasi yang bekerja diantara kedua bendab. dimanakan titik P harus ditempatkan agar kuat menda gravitasi di tempat tersebut sama dengan nol_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________7. Apabila percepatan gravitasi di permukaan bumi g = 9,9 m/s2, tentukan :a. percepatan gravitasi pada ketinggian R dari permukaan bumi! (R = jari-jari bumi )b. berapakah tinggi dari bumi jika suatu tempat memiliki g = 1,1 m/s2________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

8. Dua buah benda A dab B berturut-turut bermassa mA = 18 kg dan mB =27 kg terletak seperti pada gambar a. Hitung potensial pada titik p dan pada titik qb. Bila sebuah benda bermassa 10 kg berpakah usaha yang diprlukan untuk memindahkan benda tersebut dari titik q ke titik p___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

9. Jika perbandingan jarak planet X ke Matahari dengan jarak Bumi ke Matahari 9 : 1, hitunglah waktu yang dibutuhkan oleh planet X untuk satu kali mengitari Matahari (diketahui waktu yang dibutuhkan Bumi mengitari Matahari adalah 1 tahun) .________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

10. sebuah benda massanya50 kg ditarik sejauh 40 meter sepanjang lantai horizontal dengan gaya tetap 100 N membentuk sudut 370 terhadap arah mendatar. Jika gaya gesek terhadap lantai 50 N, maka :a. gambarkan benda berikut gayanyab. hitunglah usaha usaha oleh gaya tarik dan gaya gesekanhitunglah usaha total yang bekerja pada benda

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6 | UTS FISIKA KELAS XI MIA 2014-2015