Quantity of Charge , Q = ne
Where n = number of electrons
e = charge on one electron = -1.6 * 10 ^-19 C.
n = 50 * 10^31 electrons
Q = (50 * 10^31)*( -1.6 * 10 ^-19 ) = -8 * 10^13 C.
Note that the minus sign indicates that the charge is a negative charge.
Answer:
100N
Explanation:
Newton's third law states that whenever an object exerts a force on a second object, it exerts a force of equal magnitude and direction but in the opposite direction on the first. It is often stated as follows: Each action always opposes an equal but opposite reaction.
The subject 1 of 100kg is making a force F, to move an object from 50Kg to 2m / s ^ 2. This Force the object of 50Kg will reflect it in the opposite direction by Newton's third law.
Once the parameter of the force that both are experiencing is clarified, Newton's second law is applied to their respective calculation.

That is the force the boy exert on the man during the shove.
You need to use Planck's law:
E = h·υ = (h·c)/λ
Without making all the calculations, a fraction is bigger than another when the denominator is smaller. Therefore you need to find the smallest wavelength (λ) which is 450nm.
You could also be helped by colors: in order of decreasing energy, you have blue - green - yellow - red.
In any case, the correct answer is a).
Answer:

Where
represent the force for each of the 5 cases
presented on the figure attached.
Explanation:
For this case the figure attached shows the illustration for the problem
We have an inverse square law with distance for the force, so then the force of gravity between Earth and the spaceship is lower when the spaceship is far away from Earth.
Th formula is given by:

Where G is a constant 
represent the mass for the earth
represent the mass for the spaceship
represent the radius between the earth and the spaceship
For this reason when the distance between the Earth and the Spaceship increases the Force of gravity needs to decrease since are inversely proportional the force and the radius, and for the other case when the Earth and the spaceship are near then the radius decrease and the Force increase.
Based on this case we can create the following rank:

Where
represent the force for each of the 5 cases
presented on the figure attached.