Highest energy photon absorbed: 
Explanation:
An atom is said to be (positively) ionised when it absorbs a photon, and as a consequence, an electron becomes energetic enough to escape the atom, leaving an excess of positive charge behind.
In order for the electron to escape, the energy of the absorbed photon must be exactly equal to the (negative) energy of the level in which the electron lies.
For an hydrogen atom, the energy levels are given by

where this energy is measured in electronvolts, and n is the number of the energy level.
Since the energy is negative, this means that the electron which requires most energy is the one lying in the ground state (n=1). Therefore, for an electron in the ground state, the most energy that can be absorbed from the incoming photon is

Converting into Joules, this is equal to

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Let's assume that ground level is the height 0 meters. The change in potential energy is going to be gravitational potential energy, which is given by PE=mgh.
ΔPE=mgh-mgy
=mg(h-y)
=50(28-0)
=1400 J
This type of a problem can be solved by considering energy transformations. Initially, the spring is compressed, thus having stored something called an elastic potential energy. This energy is proportional to the square of the spring displacement d from its normal (neutral position) and the spring constant k:

So, this spring is storing almost 12 Joules of potential energy. This energy is ready to be transformed into the kinetic energy when the masses are released. There are two 0.2kg masses that will be moving away from each other, their total kinetic energy after the release equaling the elastic energy prior to the release (no losses, since there is no friction to be reckoned with).
The kinetic energy of a mass m moving with a velocity v is given by:

And we know that the energies are conserved, so the two kinetic energies will equal the elastic potential one:

From this we can determine the speed of the mass:

The speed will be 7.74m/s in in one direction (+), and same magnitude in the opposite direction (-).
Answer:
Force on superball will be 
Explanation:
We have given mass of superball m = 52 gram = 0.052 kg
Velocity change from 20 m/sec downward to 14 m/sec upward
Let downward velocity is positive then upward velocity is negative
So downward velocity is + 20 m/sec and upward velocity is -14 m/sec
Time is given as 1800 sec
We know that acceleration is rate of change of velocity
So 
According to newton second law
Force = ma = 0.052×0.0188 
Shadows are formed when an opaque object or an object that doesn't allow light to pass through is in the way or infront of etc. a source of light.