Answer:

Explanation:
When she moved a distance of 1 m from mid point she observe first destructive interference due to two speakers
so we can say that path difference of sound due to two speakers will be equal to half of the wavelength
so path difference is given as

so it will be


now we know that


now frequency of sound is given as



In the first direct detection of gravitational waves by LIGO in 2015, the waves came from the merger of two black holes. Option B is correct. This is further explained below.
<h3>What are gravitational waves?</h3>
A gravitational wave is simply defined as a ripple in space that is unseen though extremely rapid. Gravitational waves move at light speed. As they pass past, these waves compress and stretch everything in their path.
In conclusion, the merger of two black holes is the first direct detection of gravitational waves.
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Radiation is a method of heat transfer through electromagnetic waves. This transfer does not require a medium in order for heat to be transferred.
The solution is A.
Answer:
0.33 s
Explanation:
For this case, as the object is hung on the end of an unstretched spring, we can consider this system as a simple pendulum.
For this system, we can determine the period of the motion using the following formula:
T = 2π√(L/g)
Where: T = period (in sec), L = lenght of the spring, g = acceleration of garvity = 9.8 m/s²
By the exact time the object is 2.75 cm before coming to rest, that will be the lenght of the spring we can consider (2.75 cm = 0.0275 m)
Finally:
T = 2π√(0.00275/9.8)
T = 0.33 sec