Soal Sifat-sifat Gelombang Bunyi

Explanation
The correct answer is 1) dan 2). The explanation for this is that the speed of a transverse wave in a string is directly proportional to the square root of the tension in the string and inversely proportional to the square root of the mass per unit length of the string. This means that as the tension in the string increases, the speed of the wave also increases. Similarly, as the mass per unit length of the string decreases, the speed of the wave increases. Therefore, options 1) and 2) are both correct statements.

Explanation
The height or loudness of a sound is determined by its amplitude. Amplitude refers to the maximum displacement of particles in a medium from their equilibrium position when a sound wave passes through it. A larger amplitude corresponds to a louder sound, while a smaller amplitude corresponds to a softer sound. Therefore, the correct answer is amplitudo.

Explanation
The correct answer is 200. The question states that a string with a length of 50 cm is plucked, creating a fundamental frequency of 200 Hz. The speed of wave propagation in the string can be determined using the formula v = fλ, where v is the speed, f is the frequency, and λ is the wavelength. Since the fundamental frequency is given as 200 Hz, the wavelength can be calculated by dividing the speed of the wave by the frequency. As the wavelength is not provided in the question, it can be assumed that the wavelength is equal to the length of the string, which is 50 cm. Therefore, the speed of wave propagation in the string is 200 m/s.

Explanation
The correct answer is 170 m/s because the frequency of the sound heard by the listener is double the frequency of the siren. This is due to the Doppler effect, which occurs when there is relative motion between the source of sound and the listener. In this case, the frequency of the siren is 850 Hz, but the listener hears it as 1700 Hz. By using the formula for the Doppler effect, v = fλ, where v is the velocity of the wave, f is the frequency, and λ is the wavelength, we can solve for the velocity of the plane. Since the velocity of sound in air is given as 340 m/s, we can rearrange the formula to v = fλ/2 and substitute the given values to find that the velocity of the plane is 170 m/s.

Explanation
The correct answer is "Tiga perut tiga simpul". This answer is correct because it follows the pattern given in the question. The question states that when a closed pipe is blown, it produces a sound with two overtones. The given options represent different combinations of the number of knots (simpul) and the number of holes (perut) on the pipe. Among the options, only "Tiga perut tiga simpul" matches the pattern of having three knots and three holes.

Explanation
The interference between two sound sources with frequencies of 604 Hz and 600 Hz will result in a beat frequency equal to the difference between the two frequencies, which is 4 Hz. The number of beats produced in a given time period can be calculated by multiplying the beat frequency by the duration of the time period. In this case, the duration is given as ½ minute, which is equal to 30 seconds. Therefore, the number of beats produced during this time period is 4 Hz x 30 seconds = 120.

Explanation
The intensity of sound decreases as the distance from the source increases. The relationship between intensity and distance is inversely proportional, meaning that as the distance increases, the intensity decreases. In this case, the sound intensity at a distance of 2 m is given as 90 dB. Since the distance is increasing by a factor of 10 (from 2 m to 20 m), the intensity will decrease by 10 times (10 dB). Therefore, the intensity at a distance of 20 m from the source will be 90 dB - 10 dB = 80 dB. The closest option to 80 dB is 70 dB, which is the correct answer.

Explanation
The given correct answer is 6.8 Hz and 24.4 Hz. This can be explained by using the formula for the fundamental frequency of a pipe organ, which is given by f = v/2L, where f is the frequency, v is the velocity of sound, and L is the length of the pipe. Substituting the given values, we get f = 340/(2*0.25) = 6.8 Hz. The frequency of the first overtone (nada atas pertama) can be calculated by multiplying the fundamental frequency by 3, so 6.8 Hz * 3 = 24.4 Hz.

Explanation
The intensity of sound decreases as the distance from the source increases. This is because sound energy spreads out in all directions, causing the intensity to be distributed over a larger area. In this case, the intensity at a distance of 2 meters would be half of the intensity at a distance of 1 meter, resulting in an intensity of 2.10-6 watt/m2.

Explanation
When 10 machines are turned on together, the total sound intensity is calculated by adding the individual intensities. Since each machine has an average intensity of 50 dB, the total intensity would be 10 times that, which is 500 dB. However, the decibel scale is logarithmic, so to find the final intensity in dB, we need to convert it back to a linear scale. By taking the logarithm base 10 of the total intensity (500), we get 2.7. Multiplying this by 10 gives us the final intensity of approximately 27 dB. Therefore, the correct answer is 60 dB.