Answer:
Newtons law of gravitation is called the universal law of gravitation because it is applicable for all masses at all distances, independent of the medium.
Explanation:

For two masses m1 and m2 placed at a distance d, the gravitational force between them will always be given by: Fg=Gd2m1m2. That's why it is a "universal" law.
Answer:
The angle of the incident ray at the air-glass interface is 62.86°
Explanation:
Given that,
Refractive index of glass =1.60
Angle = 42°
We need to calculate the angle of the incident ray at glass-water interface
Using Snell's law

Where,
= refractive index of glass
= refractive index of water
= angle of refraction
Put the value into the formula




We need to calculate the angle of the incident ray at the air-glass interface
Using Snell's law

Where,
= refractive index of air
= refractive index of glass
= angle of incident
Put the value into the formula



Hence, The angle of the incident ray at the air-glass interface is 62.86°