Answer:
<em>2035 </em>
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Explanation:
The doctor does not travel with the woman, and therefore, he won't experience any relativistic effect on his time. The doctor will judge time by the time here on earth. Technically, the last new year's day the doctor, who is here on earth, would expect the woman to celebrate will be in 2020 + 15 years = <em>2035 </em>
<em></em>
Answer:
f=ma.......m=f/a......m=20kg
1. 
First of all, let's convert the energy of the absorbed photon into Joules:

The energy of the photon can be rewritten as:

where
h is the Planck constant
c is the speed of light
is the wavelength of the photon
Re-arranging the formula, we can solve to find the wavelength of the absorbed photon:

2. 1.24 eV
In this case, when the electron jumps from the n=4 level to the n=3 level, emits a photon with wavelength

So the energy of the emitted photon is given by the formula used previously:

and using

we find

converting into electronvolts,

EDIT: an issue in Brainly does not allow me to add the last 2 parts of the solution - I have added them as an attachment to this post, check the figure in attachment.
I think the answer is strong force.