Answer: 0.25 m/s
Explanation: Speed = wavelengt · frequency
v = λf and frequency is 1/period f = 1/T
Then v = λ/T = 5 m / 20 s = 0.25 m/s
<span>Two of them are "redshift" and "blueshift", which are used to describe an object'smotion toward or away from us in space. Redshift indicates that an object is moving away from us. "Blueshift" is a term that astronomers use to describe an object that is moving toward another object or toward us.</span>
All of them apply because they all are doing some thing to move
Answer:

Explanation:
The refractive index of a medium is given by the following formula:

where,
η = refractive index = 1.5
= angle of incidence = ?
= angle of refraction = 15°
Therefore,

