<span>When an atom undergoes decay its nucleus becomes unstable because it does not have a balance of neurons and protons. This means the atoms try to find a confirmation in which it is stable. In doing so, it is possible that the atom changes its element, and it frees a huge amount of energy in order to balance itself. This is the base of radioactivity.</span>
Answer:46.05 mm
Explanation:
Given

speed 
allowable shear stress 
Power is given by



From Torsion Formula

where J=Polar section modulus
T=Torque
=shear stress
For square cross section

where a=side of square

Substituting the values in equation 1



Answer:
F = 24 N
Explanation:
In this exercise we have a bar l = 100 m with a center of gravity x = 4 m, which force is needed to lift it from the other end
Let's use the rotational equilibrium relationship, where we consider the counterclockwise rotations as positive and fix the reference system at the point closest to the center of gravity
∑ τ = 0
F l -x W = 0
F = 
let's calculate
F =
4/100 600
F = 24 N