It is an example of reflection of wave. C.
that is an example of negative acceleration because it is slowing down
Answer:
Radio waves have a wavelength between
and 
While,
X rays have a wavelength between 1m and 10km.
=> It is one of the condition of diffraction that the obstacle (coming in the way) must be comparable with the size of the wavelength.
=> This shows, that radio waves have a wavelength which is comparable with the size of buildings and can really easily diffract through it
=> While, X-rays are big enough to diffract through the wall.
So, if an X-ray technician stands behind a wall during the use of her machine, she will remain safe.
Answer: I believe the answer is C
Explanation:
Cars are composed of hundreds of simple machines
here in the given situation if monkey starts free fall at the same instant when veterinarian shoots towards it then we know that vertical component of motion of monkey and the dart will be same as under gravity
so here the dart will always hit the monkey because they both moves under same acceleration
so here for the angle we can use

now we have
H = 3 m
L = 87.5 m
now we will have



so angle will be 1.96 degree above the ground