Answer:
v = 8.4 m/s
Explanation:
The question ays, "A longitudinal wave has a frequency of 200 Hz and a wavelength of 4.2m. What is the speed of the wave?".
Frequency of a wave, f = 200 Hz
Wavelength = 4.2 cm = 0.042 m
We need to find the speed of the wave. The formula for the speed of a wave is given by :

So, the speed of the wave is equal to 8.4 m/s.
The frequency of the wave will not change. Since the change in medium doesn't affect the source of the waves, the frequency of those waves do not change.
Hope this helps! :)
Answer:
Unknown
Explanation:
By definition, we can't observe what's inside there, because no light – no information of any kind – can escape a black hole. But astrophysical theories suggest that, at the core of a black hole, all the black hole's mass is concentrated into a tiny point of infinite density. This point is known as a singularity.
In physics, "work<span>" is when a force applied to an object moves the object in the same direction as the force. If someone pushes against a wall, no </span>work<span> is done on the system. It is calculated as follows:
Work = Force x distance
Work = 25 N x 4 meters
Work = 100 N.m</span>