Answer:
The mass of unknown object is 8.62Kg
Explanation:
To develop this problem it is necessary to apply the equations related to the Drag force and the Force of Gravity.
For the given point, that is, the moment at which the terminal velocity is reached, the two forces equalize, that is,

By definition we know that the Drag force is defined as

Where,
Drag coefficient
Density
A =Cross-sectional Area
V = Velocity
In the other hand we have,

Where,
Mass of sphere
Mass of unknown object
Equating the two equations we have to

Re-arrange for m_2,

Our values are given by,






Replacing in the equation we have,


<em>Therefore the mass of unknown object is 8.62Kg</em>
Answer:
The maximum emf that can be generated around the perimeter of a cell in this field is 
Explanation:
To solve this problem it is necessary to apply the concepts on maximum electromotive force.
For definition we know that

Where,
N= Number of turns of the coil
B = Magnetic field
Angular velocity
A = Cross-sectional Area
Angular velocity according kinematics equations is:



Replacing at the equation our values given we have that




Therefore the maximum emf that can be generated around the perimeter of a cell in this field is 
Answer:
a)The approximate radius of the nucleus of this atom is 4.656 fermi.
b) The electrostatic force of repulsion between two protons on opposite sides of the diameter of the nucleus is 2.6527
Explanation:

= Constant for all nuclei
r = Radius of the nucleus
A = Number of nucleons
a) Given atomic number of an element = 25
Atomic mass or nucleon number = 52


The approximate radius of the nucleus of this atom is 4.656 fermi.
b) 
k=
= Coulombs constant
= charges kept at distance 'a' from each other
F = electrostatic force between charges


Force of repulsion between two protons on opposite sides of the diameter



The electrostatic force of repulsion between two protons on opposite sides of the diameter of the nucleus is 2.6527