A beat is an interference pattern between two sounds of slightly different frequencies, perceived as a periodic variation in volume whose rate is the difference of the two frequencies. Frequency beat is equal to,

The reference frequency in our case would be 392Hz, and since there is the possibility of the upper and lower range for the amount of beats per second that the two possible frequencies are heard would be


Therefore the two possible frequencies the piano wire is vibrating at, would be 396Hz and 388Hz
To solve this problem we will apply the concepts related to the calculation of the speed of sound, the calculation of the Mach number and finally the calculation of the temperature at the front stagnation point. We will calculate the speed in international units as well as the temperature. With these values we will calculate the speed of the sound and the number of Mach. Finally we will calculate the temperature at the front stagnation point.
The altitude is,

And the velocity can be written as,


From the properties of standard atmosphere at altitude z = 20km temperature is



Velocity of sound at this altitude is



Then the Mach number



So front stagnation temperature



Therefore the temperature at its front stagnation point is 689.87K
Mutualism is a long-term relationship where two organisms interact in such a way that both of them benefits from that relationship.
For example, there is a relationship between a bird called "oxpecker", and a rhino. While the bird eats the harmful bugs (eg. tick) on the rhino's skin and relieves its hunger; the rhino gets rid of the bugs that harm it.
Scientists gather a new evidence like let me say for example jj Thompson said that an atoms is the least particles of an element but according to our definition an atom is the smallest particles of an element so you see
Answer:
1. 23°
2. 65°
Explanation:
1.
The law of reflection provides that for the same medium, the angle of reflection equals the angle of incidence.
Similarly, here, angle of incidence and reflection will be 46°÷2=23°
2. Since the normal, angles of reflection and incidence lie on the same plane and also the angles of reflection and incidence are equal then the angle between the plane of the mirror and the reflected beam will be given by 90-25=65°