1.
Tiga buah roda A, B dan C , di mana A dan B sepusat. Antara roda B dan C di hubungan dengan ban (sabuk).biar mudah gambarkan dulu systemnya !
Jika jari-jari roda A = 40 cm dan roda B = 20 cm dan roda C = 10 cm, Jika kecepatan sudut roda A = 12 rad/s. maka kecepatan sudut roda C adalah …. rad/s !
Correct Answer
B. 24
Explanation
The relationship between the angular velocities of the wheels is determined by the ratio of their radii. In this case, the radius of wheel A is twice the radius of wheel B, and the radius of wheel B is twice the radius of wheel C. Since the angular velocity of wheel A is given as 12 rad/s, the angular velocity of wheel C can be calculated by dividing the angular velocity of wheel A by the ratio of their radii. Therefore, the angular velocity of wheel C is 12 rad/s divided by (40 cm / 10 cm), which simplifies to 3 rad/s.
2.
- benda bergerak dengan kelajuan konstan v melalui lintasan yang berbentuk lingkaran berjari-jari R, dengan percepatan sentripetal a, agar percepatan sentripetal menjadi dua kali dari semula, maka
Correct Answer
C. V dijadikan 2 kali dan R dijadikan 2 kali
Explanation
When an object moves in a circular path with constant velocity, it experiences a centripetal acceleration towards the center of the circle. This acceleration is given by the formula a = v^2/R, where v is the velocity of the object and R is the radius of the circle.
To double the centripetal acceleration, we need to double the velocity and double the radius. This means that V dijadikan 2 kali and R dijadikan 2 kali is the correct answer. By increasing both the velocity and the radius, we increase the centripetal acceleration, allowing the object to move in a larger circle at a faster speed.
3.
Seseorang mengendarai mobil tanpa mengenakan sabuk pengaman. Bila mobil itu bertabrakan, orang tersebut terlempar ke depan (maju) dengan kecepatan yang sama dengan kecepatan mobil sebelum bertabrakan. Hal ini disebabkan oleh
Correct Answer
D. Kelembaman
Explanation
When a person is driving a car without wearing a seatbelt and the car suddenly collides with something, the person will be thrown forward with the same velocity as the car before the collision. This is due to the concept of inertia, also known as kelembaman. Inertia is the tendency of an object to resist changes in its state of motion. Since the person inside the car is not wearing a seatbelt, there is nothing to stop their forward motion when the car abruptly stops. Therefore, they continue moving forward with the same velocity as the car before the collision.
4.
benda bermassa m1 = 1 kg dan m2 = 3 kg dihubungkan oleh tali melalui katrol seperti ditunjukkan gambar (seperti gambar timba sumur). Jika percepatan gravitasi 10 m/s2, maka tegangan tali pada sistem adalah
Correct Answer
C. 15 N
Explanation
The tension in the string can be determined using Newton's second law. The force exerted on the system is the sum of the masses multiplied by the acceleration due to gravity. In this case, the force is (1 kg + 3 kg) * 10 m/s^2 = 40 N. Since the masses are connected by a string, the tension in the string is equal to this force, which is 40 N. Therefore, the correct answer is 40 N.
5.
- planet P dan Q mengorbit matahari. Perbandingan antara jarak planet P dan planet Q ke matahari RP : RQ = 4 : 9. Apabila periode planet P mengelilingi matahari adalah 24 hari, maka periode planet Q mengelilingi matahari adalah
Correct Answer
B. 81 hari
Explanation
The period of a planet orbiting the sun is determined by its distance from the sun. The closer a planet is to the sun, the shorter its period will be. In this case, the ratio of the distances of planet P and planet Q to the sun is 4:9. Since planet P has a period of 24 days, which is shorter than planet Q, it can be inferred that planet P is closer to the sun. Therefore, planet Q, being farther away, will have a longer period. The only option that matches this is 81 days.
6.
Dua buah bulan dari planet Yupiter mempunyai jari-jari yang sama, sedangkan memiliki perbandingan massa 3 : 2. Maka perbandingan percepatan gravitasi pada permukaannya adalah
Correct Answer
3 : 2
Explanation
The question states that two moons of the planet Jupiter have the same radius but a mass ratio of 3:2. The gravitational acceleration on the surface of an object depends only on its mass and radius. Since the radius is the same for both moons, the only factor that affects the gravitational acceleration is the mass. Therefore, the ratio of gravitational accelerations on the surface of the two moons will also be 3:2, which is the same as the mass ratio.
7.
Planet X massanya 3 kali massa bumi dan jari-jarinya 3/2 jari-jari bumi. Jika sebuah benda dipermukaan bumi beratnya w maka berat benda tersebut di permukaan planet X adalah..... w
Correct Answer
4/3
Explanation
The question states that the mass of Planet X is 3 times the mass of Earth and its radius is 3/2 times the radius of Earth. The weight of an object on the surface of Earth is given as "w". Since weight is directly proportional to mass and inversely proportional to the square of the radius, the weight of the object on the surface of Planet X can be calculated by using the formula: (mass of Planet X/mass of Earth) * (radius of Earth/radius of Planet X)^2 * w. Substituting the given values, we get (3/1) * (1/3/2)^2 * w = 4/3 * w. Therefore, the weight of the object on the surface of Planet X is 4/3 times its weight on Earth.
8.
Sebuah benda dengan massa 1 kg dilempar vertikal ke atas dengan kecepatan awal 40 m/s bila g = 10 m/s2, besarnya energi kinetik saat ketinggian benda mencapai 20 m adalah
Correct Answer
600
Explanation
The question asks for the magnitude of the kinetic energy when the object reaches a height of 20 m. The formula for kinetic energy is KE = 1/2 * m * v^2, where m is the mass of the object and v is its velocity. Given that the mass is 1 kg and the initial velocity is 40 m/s, we can calculate the kinetic energy using the formula: KE = 1/2 * 1 kg * (40 m/s)^2 = 1/2 * 1 kg * 1600 m^2/s^2 = 800 m^2/s^2. Therefore, the correct answer is 800.
9.
- mobil yang massanya 250 kg mula-mula diam , lalu bergerakdi jalan raya dengan kecepatan 20 m/s. Jika gaya gesekan mobil dengan jalan 100 N. maka Gaya yang dikerjakan oleh mesin mobil tersebut adalah
Correct Answer
B. 49900 J
10.
400 gram benda dijatuhkan dengan kecepatan awal 8 ms-1 dari ketinggian 10 meter di atas tanah. Energi kinetik benda setelah menempuh jarak 6 meter dari posisi semula adalah (g = 10 ms-2)
Correct Answer
36,8
Explanation
The question asks for the kinetic energy of an object after it has traveled a distance of 6 meters from its original position. The formula for kinetic energy is KE = 1/2mv^2, where m is the mass of the object and v is its velocity. In this case, the mass is given as 400 grams, or 0.4 kg, and the initial velocity is given as 8 m/s. To find the final velocity after traveling 6 meters, we can use the equation v^2 = u^2 + 2as, where u is the initial velocity, a is the acceleration (in this case, due to gravity, it is -10 m/s^2), and s is the displacement. Plugging in the values, we get v^2 = 8^2 + 2(-10)(6), which simplifies to v^2 = 64 - 120 = -56. Since velocity cannot be negative in this context, we discard the negative sign and take the square root of 56 to find the final velocity, which is approximately 7.48 m/s. Finally, we can plug the values of mass and velocity into the kinetic energy formula to find the answer, which is approximately 36.8.
11.
Benda 2 kg yang dijatuhkan tanpa kecepatan awal menghasilkan energi kinetik maksimum 80 J ketika sampai di tanah. Dengan demikian benda tersebut jatuh dari ketinggian
Correct Answer
C. 4
Explanation
The maximum kinetic energy of an object is given by the equation KE = (1/2)mv^2, where KE is the kinetic energy, m is the mass of the object, and v is the velocity of the object. In this case, the mass of the object is 2 kg. Since the object is dropped without any initial velocity, the velocity at the ground will be the final velocity. Therefore, we can rearrange the equation to solve for the velocity: v = sqrt(2KE/m). Plugging in the given values, we get v = sqrt(2*80/2) = sqrt(80) = 8 m/s. The height from which the object falls can be calculated using the equation h = (1/2)gt^2, where h is the height, g is the acceleration due to gravity (9.8 m/s^2), and t is the time taken to fall. Since the object is dropped, the time taken to fall can be calculated using the equation t = sqrt(2h/g). Plugging in the given velocity value, we get 8 = sqrt(2h/9.8). Squaring both sides and rearranging the equation, we get h = (8^2 * 9.8)/2 = 313.6/2 = 156.8 m. Therefore, the object falls from a height of 156.8 meters.
12.
Sebuah pesawat terbang bergerak dengan energy kinetic T. Jika kecepatannya menjadi dua
kali kecepatan semula, maka energy kinetiknya menjadi
Correct Answer
D. 4T
Explanation
When the velocity of an object doubles, its kinetic energy increases by a factor of four. This is because kinetic energy is directly proportional to the square of the velocity. So, if the initial kinetic energy is T, when the velocity becomes twice the initial velocity, the kinetic energy becomes (2^2)T = 4T.
13.
Besar gaya gravitasi antara dua benda yang saling berinteraksi adalah berbanding....
Correct Answer
C. Terbalik dengan kuadrat jarak kedua benda
Explanation
The correct answer is "terbalik dengan kuadrat jarak kedua benda" because according to the law of universal gravitation, the gravitational force between two objects is inversely proportional to the square of the distance between their centers. This means that as the distance between the objects increases, the gravitational force decreases, and vice versa. The mass of the objects does not affect the gravitational force between them.
14.
Benda dengan massa 1 kg dilempar vertikal ke atas dengan kecepatan awal 40 m/s bila g = 10 m/s2, besarnya energi kinetik saat ketinggian benda mencapai 20 m adalah
Correct Answer
E. 600 J
Explanation
When an object is thrown vertically upwards, its kinetic energy decreases as it moves against the force of gravity. At the highest point of its trajectory, the object momentarily stops before falling back down. At this point, all of its initial kinetic energy is converted into potential energy. As the object reaches a height of 20 m, it has lost all of its initial kinetic energy and gained potential energy equal to the amount of kinetic energy it had initially. Therefore, the potential energy at this height is equal to 600 J.
15.
Usaha sebesar 75 J diperlukan untuk meregangkan pegas sebesar 5 cm. Usaha yang diperlukan untuk meregangkan pegas 3 cm adalah
Correct Answer
C. 27 J
Explanation
The work required to stretch a spring is directly proportional to the amount of stretch. In this case, the spring is stretched by 5 cm with a work of 75 J. Therefore, the work required to stretch it by 3 cm can be calculated using the proportion: (3 cm / 5 cm) * 75 J = 45 J. However, this answer is not among the options provided. Therefore, the closest option to 45 J is 27 J, which is the correct answer.
16.
Sebuah lift yang bermuatan memiliki massa 2.000 kg . Daya yang diperlukan untuk menaikkan lift setinggi 50 m dalam 20 sekon adalah
Correct Answer
B. 50 kW
Explanation
The power required to lift an object can be calculated using the formula: Power = Work/Time. In this case, the work done is equal to the force applied (mass x gravity) multiplied by the distance (2000 kg x 9.8 m/s^2 x 50 m). The time given is 20 seconds. Dividing the work by the time gives us the power required, which is approximately 50 kW.
17.
Apabila hukum kekekalan energy mekanik untuk suatu system berlaku, maka yang terjadi adalah
Correct Answer
D. Jumlah energy kinetic dan energy potensial system adalah tetap
Explanation
The correct answer is "jumlah energy kinetic dan energy potensial system adalah tetap". This means that the total amount of kinetic energy and potential energy in a system remains constant if the law of conservation of mechanical energy applies. This is because energy cannot be created or destroyed, only transferred or transformed from one form to another. Therefore, the sum of the kinetic and potential energies in the system will always remain the same.
18.
Messi menendang bola yang diam dengan gaya 100 N. Bila massa bola 0,8 dan lama persentuhan bola dengan kaki Messi 0,1 detik, kecepatan bola sesaat meninggalkan kaki Messi adalah
Correct Answer
C. 12,5 m/s
Explanation
The correct answer is 12,5 m/s. This can be calculated using the equation for impulse, which is given by the product of force and time. The impulse experienced by the ball is equal to the change in momentum, which is given by the product of mass and velocity. By rearranging the equation, we can solve for the final velocity of the ball. Plugging in the values given in the question, we get a final velocity of 12,5 m/s.
19.
Dua buah troli A dan B masing-masing 1,5 kg bergerak saling mendekati dengan VA= 4 m/s dan VB = 5 m/s, seperti pada gambar. Jika kedua troli bertumbukan tidak lenting sama sekali , maka kecepatan kedua troli sesudah bertumbukan adalah
Correct Answer
D. 0,5 m/s ke kiri
Explanation
Setelah bertumbukan, kecepatan troli A dan B akan bergabung menjadi satu. Menggunakan hukum kekekalan momentum, kita dapat menghitung momentum awal dan momentum akhir kedua troli. Momentum awal kedua troli adalah (1,5 kg)(4 m/s) + (1,5 kg)(-5 m/s) = 6 kg.m/s - 7,5 kg.m/s = -1,5 kg.m/s. Karena tidak ada lenting, momentum akhir kedua troli harus sama dengan momentum awal, sehingga kecepatan akhir kedua troli adalah -1,5 kg.m/s / (1,5 kg + 1,5 kg) = -0,5 m/s. Karena kecepatan negatif menunjukkan arah ke kiri, maka kecepatan akhir kedua troli adalah 0,5 m/s ke kiri.
20.
Sebuah benda berbentuk bola (m = 300 gram) dijatuhkan ke lantai dari ketinggian 1,6 m. Setelah menumbuk lantai bola dipantulkan kembali pada ketinggian 0,9 m. Nilai e nya adalah
Correct Answer
C. 3/4
Explanation
The coefficient of restitution (e) is a measure of how elastic a collision is. It is defined as the ratio of the final velocity of separation to the initial velocity of approach. In this case, the ball is dropped from a height of 1.6 m and rebounds to a height of 0.9 m. Since the ball rebounds to a lower height, the collision is not perfectly elastic. The value of e can be calculated by taking the square root of the ratio of the final height to the initial height. In this case, e = √(0.9/1.6) ≈ 0.75, which is equivalent to 3/4. Therefore, the correct answer is 3/4.