1° Prueba Online De FÍsica

Explanation
La afirmación de que A tiene mayor longitud de onda que B es correcta. Esto se puede determinar observando la figura proporcionada, donde la onda A tiene crestas más separadas entre sí en comparación con la onda B. La longitud de onda se define como la distancia entre dos puntos consecutivos en una onda que están en fase, por lo que si los puntos de la onda A están más separados, su longitud de onda debe ser mayor que la de la onda B.

Explanation
The question states that a wave travels along an inextensible string and covers a distance of 13.5m in 0.5s. The speed of the wave can be calculated by dividing the distance traveled (13.5m) by the time taken (0.5s), which gives a speed of 27 m/s. The wavelength of a wave is the distance between two consecutive points in the wave that are in phase. The formula to calculate wavelength is wavelength = speed / frequency. Since the frequency is not given in the question, we cannot directly calculate the wavelength. However, we can assume that the wave is a simple harmonic wave and the speed is constant. In this case, the wavelength is inversely proportional to the frequency. Therefore, if the speed is constant, a shorter wavelength would mean a higher frequency. Since the options given do not include a higher frequency, we can conclude that the wavelength must be longer. Among the options, 9m is the longest wavelength, so it is the correct answer.

Explanation
The correct answer is "I y III". This means that both statement I and statement III are incorrect. Statement I suggests that observer A is approaching point C, but there is no information given in the question about the motion of observer A. Therefore, this statement cannot be determined. Statement III suggests that both points A and B are at rest, but since the question states that there is a wave propagating in the medium, it implies that there is some motion happening. Therefore, this statement is also incorrect.

Explanation
El punto D está vibrando con la mayor amplitud.

Explanation
The correct answer is "En la circunferencia D". This means that in order to hear the note "La" of 440 Hz, one must blow into the holes on the circumference D. This suggests that the holes on circumference D are spaced equidistantly in a way that creates a frequency of 440 Hz when the airflow is disturbed by blowing into them. The other circumferences (A, B, C, E) may not have the same spacing or arrangement of holes, which is why they are not the correct answer.

Explanation
La longitud de onda se refiere a la distancia entre dos puntos consecutivos en una onda, como por ejemplo entre el punto P y el punto R. Por lo tanto, la respuesta correcta es "la distancia entre P y R".

Explanation
P and Q are standing at different distances from the siren, but they both hear the same sound. This suggests that the sound has the same frequency, intensity, and wavelength at both locations. Therefore, all three statements (I, II, and III) are correct.

Explanation
When two waves superpose, the resulting amplitude is equal to the sum of the individual amplitudes. In this case, the two pulses have amplitudes of 5 cm and 3 cm respectively. When they overlap, their maximum amplitudes add up, resulting in a total amplitude of 5 cm + 3 cm = 8 cm. Therefore, the correct answer is 8 cm, not 2 cm as stated in the given answer.

Explanation
The diagrams represent the profiles of two sound waves P and Q of equal amplitude traveling in the same homogeneous medium. From the diagrams, we can observe that the waves have different frequencies and different wavelengths. Therefore, we can conclude that only statements II and III are correct, which means that the sound waves have different frequencies and different wavelengths.

Explanation
The correct answer is 2,25. The figure shows a wave profile with two complete wavelengths between points P and Q. Each complete wavelength corresponds to one full cycle of the wave, which is the distance between two consecutive peaks or troughs. By counting the number of complete wavelengths, we can determine that there are 2,25 wavelengths between points P and Q.

Explanation
The correct answer is "Solo III". This means that only statement III is correct. The explanation for this is that the question states that the waves have the same velocity, which means they travel at the same speed. Since the speed of a wave is equal to the product of its frequency and wavelength, if the speed is the same for both waves, then their wavelengths must also be the same. Therefore, statement I is incorrect. Additionally, the question does not provide any information about the frequencies of the waves, so statement II cannot be determined. However, the question does state that the amplitudes of the waves are 3 and 6 cm respectively, so statement III is correct.

Explanation
The person can only hear the echo if the time it takes for the sound to travel to the cliff and back is longer than the time period of the sound wave. The time period of a sound wave is the inverse of its frequency, so in this case, the time period is 1/20 s. The distance the sound travels is the speed of sound multiplied by the time it takes, so the person needs to be at a distance of at least (340 m/s * 1/20 s) = 340/20 m from the cliff to hear the echo.