Answer:

Explanation:
For sound waves we have v=d/t where v is the speed of sound and d the distance between the astronauts, while for electromagnetic waves we have c=D/t where c is the speed of light and D the distance between the spaceship and Earth. <em>We have written both times as the same</em> because is what is imposed by the problem, so we have t=d/v=D/c, which means:

And for our values:

A) red light
red lights are an example of an electromagnetic wave. visible lights are the only electromagnetic waves we can actually see on the spectrum. red, in particular has the biggest wavelength.
b) ocean waves
ocean waves are not an electromagnetic wave. in fact, it’s a mechanical wave. electromagnetic waves can travel through a vacuum, that is empty space, but mechanical waves cannot.
c) sound waves
sound waves are also not an electromagnetic wave. it’s a mechanical wave. you cannot hear electromagnetic waves.
d) earthquakes
an earthquake is also not an example of electromagnetic waves. it’s a mechanical wave.
hope this helps!
Answer:
Solution given:
No of waves[N] =20crests & 20 troughs
=20waves
Time[T]=4seconds
distance[d]=3cm=0.03m
Now
<u>Wave</u><u> </u><u>length</u><u>=</u>3cm=3 × 
<u>Frequency</u>=
=
=5Hertz
and
Wave speed:wave length×frequency=3 ×
×5=1.5 ×
.