Answer:
Velocidad = 500 m/s
Explanation:
Dados los siguientes datos;
Distancia = 90 km
Tiempo = 3 horas
Conversión;
Por distancia:
1 kilómetro = 1000 metros
90 kilómetros = 90 * 1000 = 90,000 metros
Para el tiempo:
1 hora = 60 segundos
3 horas = 60 * 3 = 180 segundos
Para encontrar la velocidad en m/s;
Matemáticamente, la velocidad viene dada por la ecuación;
Sustituyendo en la fórmula, tenemos;
Velocidad = 90000/180
Velocidad = 500 m/s
When light moves from a medium with higher refractive index to a medium with lower refractive index, the critical angle is the angle above which there is no refracted ray, and it is given by:

(2)
where

is the refractive index of the second medium and

is the refractive index of the first medium.
We can find the ratio

by using Snell's law:

(1)
where

is the angle of incidence

is the angle of refraction
By using the data of the problem and re-arranging (1), we find

and if we use eq.(2) we can now find the value of the critical angle:
Answer:
nuclear energy is a energy that holds together of atoms
light energy is a kind of kinetic with the ability to make types of light visible to human eyes