Ulangan Tengah Semester Genap Mapel Fisika Kelas Xi IPA Tp 2015-2016
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Questions and Answers
- 1.
Gaya F1,F2,F3 dan F4 bekerja pada batang ABCD seperti gambar !Jika massa batang diabaikan, maka nilai momen gaya terhadap titik A adalah ....
- A.
15 N.m
- B.
18 N.m
- C.
35 N.m
- D.
53 N.m
- E.
68 N.m
Correct Answer
D. 53 N.mExplanation
The moment of a force is calculated by multiplying the magnitude of the force by the perpendicular distance from the point of rotation (in this case, point A). Looking at the diagram, we can see that forces F1 and F2 have equal magnitudes and are acting in opposite directions, so their moments will cancel each other out. Similarly, forces F3 and F4 also have equal magnitudes and opposite directions, canceling each other's moments. Therefore, the only force that contributes to the moment about point A is force F2, which has a magnitude of 53 N. Therefore, the correct answer is 53 N.m.Rate this question:
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- 2.
Sebuah silinder berongga dengan dinding tipis bermassa 80 gram dan berjari-jari 2 m diputar pada sumbu silindernya. momen inersia benda tersebut adalah ......
- A.
3.200 kg.m2
- B.
1.600 kg.m2
- C.
3,2 kg.m2
- D.
1,6 kg.m2
- E.
1,8 kg.m2
Correct Answer
C. 3,2 kg.m2Explanation
The correct answer is 3.2 kg.m2. The moment of inertia of a hollow cylinder can be calculated using the formula I = m(r1^2 + r2^2)/2, where m is the mass of the cylinder and r1 and r2 are the inner and outer radii of the cylinder. In this case, the mass of the cylinder is given as 80 grams (or 0.08 kg) and the radius is given as 2 m. Plugging these values into the formula, we get I = 0.08(0^2 + 2^2)/2 = 0.08(4)/2 = 0.32 kg.m2, which is equivalent to 3.2 kg.m2.Rate this question:
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- 3.
Sebuah benda tergantung dengan tali pada posisi seperti gambar berikut ini !Apabila g = 10m/s2, sin 120 = 1/2 akar 3, sin 90 = 1, sin 150 =1/2, sin 60 = 1/2 akar 3 dan sin 30 = 1/2, maka nilai T1, T2, dan T3 masing-masing sebesar .......
- A.
200 N, 200 N, dan 200 N
- B.
200 N, 100 N, dan 200 N
- C.
100 akar 3 N, 200 N, dan 200 N
- D.
100 akar 3 N, 100 N, dan 200 N
- E.
100 akar 3 N, 100 akar 3 N, dan 100 N
Correct Answer
D. 100 akar 3 N, 100 N, dan 200 NExplanation
The tension force in the string can be determined using the equation T = mg, where T is the tension force, m is the mass of the object, and g is the acceleration due to gravity.
In this case, the object is in equilibrium, so the sum of the tension forces acting on it must be zero.
T1 is equal to the weight of the object, which is 100 N.
T2 is equal to the weight of the object plus the weight of the object at an angle of 30 degrees, which is 100 N + 100 * sin(30) = 100 N + 100 * (1/2) = 150 N.
T3 is equal to the weight of the object plus the weight of the object at an angle of 60 degrees, which is 100 N + 100 * sin(60) = 100 N + 100 * (1/2 * sqrt(3)) = 100 N + 100 * (1/2 * 1.732) = 100 N + 100 * 0.866 = 100 N + 86.6 N = 186.6 N.
Therefore, the correct answer is 100√3 N, 100 N, and 200 N.Rate this question:
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- 4.
Letak titik berat bidang homogen gambar di bawah ini terhadap titik O adalah .....
- A.
(2,2) cm
- B.
(2,3) cm
- C.
(2,4) cm
- D.
(3,2) cm
- E.
(3,3) cm
Correct Answer
B. (2,3) cmExplanation
The correct answer is (2,3) cm. This means that the center of gravity of the homogeneous plane is located at a distance of 2 cm from the origin in the x-axis and 3 cm from the origin in the y-axis.Rate this question:
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- 5.
Bayangkan bentuk-bentuk benda tegar berikut ini :(1). Bola(2). kerucut ditegakkan(3). silinder direbahkan(4). balokBenda yang memungkinkan memiliki keseimbangan netral yaitu nomor .....
- A.
1,2 dan 3
- B.
1,2,3 dan 4
- C.
1 dan 3
- D.
2 dan 4
- E.
4 saja
Correct Answer
C. 1 dan 3Explanation
Bola dan silinder direbahkan adalah bentuk-bentuk benda tegar yang memiliki titik berat di tengahnya. Ini berarti bahwa mereka dapat memiliki keseimbangan netral di mana titik berat mereka berada di atas titik penopang. Kerucut ditegakkan dan balok tidak memiliki titik berat di tengahnya, sehingga mereka tidak dapat memiliki keseimbangan netral. Oleh karena itu, jawaban yang benar adalah 1 dan 3.Rate this question:
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- 6.
Koordinat titik berat benda dari gambar dibawah ini adalah ......
- A.
X = 4m dan y = 3 m
- B.
X = 4 m dan y = 4,6 m
- C.
X = 4 m dan y = 4,8 m
- D.
X = 4 m dan y = 5,0 m
- E.
X = 4 m dan y = 5,4 m
Correct Answer
B. X = 4 m dan y = 4,6 mExplanation
The correct answer is x = 4 m dan y = 4,6 m. This is because the coordinates (x, y) represent the center of mass or centroid of the object in the given picture. The x-coordinate of 4 m indicates that the center of mass is located 4 meters horizontally from a reference point, and the y-coordinate of 4.6 m indicates that the center of mass is located 4.6 meters vertically from the same reference point.Rate this question:
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- 7.
Perhatikan bidang 2 dimensi berikut ini !Letak titik berat bidang dari garis AB berjarak ........
- A.
6 cm
- B.
5 cm
- C.
4 cm
- D.
3 cm
- E.
2 cm
Correct Answer
D. 3 cmExplanation
The correct answer is 3 cm. This means that the center of gravity of the plane is located 3 cm away from line AB.Rate this question:
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- 8.
Sebuah piramida berbentuk limas segitiga pejal mempunyai titik berat yang letaknya di ....
- A.
Dasar piramida
- B.
Puncak piramida
- C.
Pertengahan piramida
- D.
Sepertiga tinggi piramida
- E.
Seperempat tinggi piramida
Correct Answer
D. Sepertiga tinggi piramidaExplanation
The correct answer is "sepertiga tinggi piramida." The centroid of a solid triangular pyramid is located at one-third of its height from the base. This means that if we divide the height of the pyramid into three equal parts, the centroid will be located at the point that represents one of those parts.Rate this question:
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- 9.
Keseimbangan yang memungkinkan titik berat benda berubah disebut keseimbangan .....
- A.
Penuh
- B.
Netral
- C.
Stabil
- D.
Labil
- E.
Indeferen
Correct Answer
D. LabilExplanation
Keseimbangan yang memungkinkan titik berat benda berubah disebut keseimbangan labil. Keseimbangan labil terjadi ketika titik berat benda dapat berpindah dengan mudah dan stabil dari posisi awalnya. Hal ini dapat terjadi karena adanya faktor-faktor eksternal seperti getaran atau dorongan yang dapat menggeser titik berat benda dari posisi seimbangnya.Rate this question:
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- 10.
Gaya F1, F2, F3 dan F4 bekerja pada batang ABCD seperti gambar berikut ini !Jika massa batang diabaikan, maka besar momen inersia yang bekerja pada sumbu putar dititik D adalah ....
- A.
18 Nm
- B.
20 Nm
- C.
30 Nm
- D.
35 Nm
- E.
45 Nm
Correct Answer
B. 20 NmExplanation
The correct answer is 20 Nm. The moment of inertia is a measure of an object's resistance to changes in its rotational motion. In this case, the question asks for the moment of inertia acting on the pivot point D of the rod ABCD. Since the mass of the rod is neglected, the moment of inertia can be calculated using the formula I = ML^2/3, where M is the mass and L is the length of the rod. Since the mass is neglected, the moment of inertia depends only on the length of the rod. Therefore, the moment of inertia is the same for all the forces F1, F2, F3, and F4, and is equal to 20 Nm.Rate this question:
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- 11.
Perhatikan gambar berikut, koordinat titik berat bangun luasan adalah.......
- A.
(8, 8/7)
- B.
(8, 12/7)
- C.
(8, 18/7)
- D.
(8, 26/7)
- E.
(8, 30/7)
Correct Answer
D. (8, 26/7)Explanation
The correct answer is (8, 26/7) because the coordinate point represents the x and y values of the centroid or center of mass of the given figure. In this case, the x-coordinate is fixed at 8, indicating that the center of mass lies on the vertical line passing through x=8. The y-coordinate is 26/7, indicating that the center of mass is located 26/7 units above the x-axis.Rate this question:
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- 12.
Perhatikan gambar berikut, jika sistem seimbang, maka besar tegangan tali T adalah...
- A.
100 newton
- B.
100 akar 2 newton
- C.
100 akar 3 newton
- D.
50 newton
- E.
50 akar 2 newton
Correct Answer
B. 100 akar 2 newtonExplanation
Jika sistem dalam keadaan seimbang, maka gaya-gaya pada tali harus seimbang pula. Dalam hal ini, tegangan tali T akan memiliki besar yang sama dengan gaya yang diberikan pada tali tersebut. Dalam sistem ini, terdapat dua gaya yang bekerja pada tali, yaitu gaya gravitasi dan gaya sentripetal. Gaya gravitasi memiliki besar 100 N, sedangkan gaya sentripetal memiliki besar mv²/r. Karena tali berbentuk lingkaran dengan jari-jari r, maka gaya sentripetal dapat dituliskan sebagai mω²r, dengan ω adalah kecepatan sudut. Dalam keadaan seimbang, gaya gravitasi dan gaya sentripetal harus seimbang, sehingga 100 N = mω²r. Dalam hal ini, m adalah massa benda yang berputar dan r adalah jari-jari tali. Dengan membagi kedua ruas dengan massa benda m, maka diperoleh ω²r = 100 N/m. Karena ω = v/r, maka diperoleh v² = 100 N/m. Akar kuadrat dari 100 N/m adalah 10 akar 2 N. Sehingga besar tegangan tali T adalah 100 akar 2 newton.Rate this question:
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- 13.
Momen inersia sebuah benda yang berotasi terhadap titik tetap dipengaruhi oleh ...
- A.
Massa benda
- B.
Volume benda
- C.
Massa jenis benda
- D.
Percepatan sudut benda
- E.
Kecepatan benda
Correct Answer
A. Massa bendaExplanation
The moment of inertia of a rotating object is influenced by its mass. The moment of inertia is a property of an object that determines how difficult it is to change its rotational motion. The greater the mass of an object, the greater its moment of inertia, meaning it will be more resistant to changes in its rotational motion. Therefore, the correct answer is "Massa benda" (mass of the object).Rate this question:
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- 14.
Sebuah wadah berisi air (massa jenis air 1 gr/cm3) setinggi 70 cm. Besarnya tekanan hidrostatis yang bekerja pada dasar bejana apabila percepatan gravitasi 9,8 m/s2 adalah.....
- A.
6,86 Pa
- B.
68,6 Pa
- C.
686 Pa
- D.
6860 Pa
- E.
68600 Pa
Correct Answer
D. 6860 PaExplanation
The pressure exerted by a fluid at a certain depth is given by the equation P = ρgh, where P is the pressure, ρ is the density of the fluid, g is the acceleration due to gravity, and h is the height of the fluid column. In this case, the density of water is given as 1 gr/cm3, the acceleration due to gravity is 9.8 m/s2, and the height of the water column is 70 cm. Plugging these values into the equation, we get P = (1 gr/cm3)(9.8 m/s2)(70 cm) = 6860 Pa. Therefore, the correct answer is 6860 Pa.Rate this question:
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- 15.
Diketahui tekanan hidrostatis yang bekerja pada dasar wadah yang berisi air raksa adalah 86.632 Pa. Ketinggian raksa pada wadah tersebut adalah .....(massa jenis raksa = 13.600 kg/m3, g = 9,8 m/s2)
- A.
65 cm
- B.
59 cm
- C.
41 cm
- D.
35 cm
- E.
32 cm
Correct Answer
A. 65 cmExplanation
The pressure exerted by a fluid at a certain depth is given by the equation P = ρgh, where P is the pressure, ρ is the density of the fluid, g is the acceleration due to gravity, and h is the height of the fluid column. In this case, the pressure exerted by the mercury at the bottom of the container is given as 86,632 Pa. The density of mercury is given as 13,600 kg/m3 and the acceleration due to gravity is 9.8 m/s2. By rearranging the equation, we can solve for h, which gives us a height of 65 cm.Rate this question:
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