Answer with Explanation:
We are given that
Radius of solid core wire=r=2.28 mm=

Radius of each strand of thin wire=r'=0.456 mm=
Current density of each wire=
a.Area =
Where 
Using the formula
Cross section area of copper wire has solid core =
Current density =
Using the formula


Total number of strands=19
Area of strand wire=




b.Resistivity of copper wire=
Length of each wire =6.25 m
Resistance, R=
Using the formula
Resistance of solid core wire=
Resistance of strand wire=
Answer:
Therefore the required solution is

Explanation:
Given vibrating system is

Consider U(t) = A cosωt + B sinωt
Differentiating with respect to t
U'(t)= - A ω sinωt +B ω cos ωt
Again differentiating with respect to t
U''(t) = - A ω² cosωt -B ω² sin ωt
Putting this in given equation


Equating the coefficient of sinωt and cos ωt
.........(1)
and

........(2)
Solving equation (1) and (2) by cross multiplication method


and 
Therefore the required solution is

Answer:
b) Document lessons learned.
Explanation:
First he should do documentation
then C
then D
then A
Work = (displacement) x (force in the direction of the displacement)
Since none of the force is in the direction of the displacement, the work it does
is zero. Something else is making the object move. It's not the 20N force.