A) 1.55
The speed of light in a medium is given by:

where
is the speed of light in a vacuum
n is the refractive index of the material
In this problem, the speed of light in quartz is

So we can re-arrange the previous formula to find n, the index of refraction of quartz:

B) 550.3 nm
The relationship between the wavelength of the light in air and in quartz is

where
is the wavelenght in quartz
is the wavelength in air
n is the refractive index
For the light in this problem, we have

Therefore, we can re-arrange the equation to find
, the wavelength in air:

The hang time of the ball is 4.08 s
Explanation:
The ball is in free fall motion: this means that it is acted upon gravity only, so its acceleration is the acceleration of gravity,

downward (the negative sign refers to the downward direction).
Since this is a uniformly accelerated motion, we can solve the problem by using the following suvat equation:

where
v is the final velocity
u is the initial velocity
a is the acceleration
t is the time
First we calculate the time it takes for the ball to reach the maximum height, where the velocity is zero:
v = 0
Substituting:
u = +20 m/s

we find t

The motion of the ball is symmetrical, so the total time of flight is just twice the time needed to reach the maximum height, therefore:

Learn more about free fall:
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#LearnwithBrainly
Explanation:
A simple harmonic oscillation is an oscillator that is neither driven nor damped.
<u><em>It's called geothermal energy, and is present due to the incredible amount of heat present in Earth's interior from radioactive decay, friction, and residual heat from Earth's formation.</em></u>