Which of the three substances has the greatest permeability?
a. gravel
b. sand
c. silt
d. all are equal?

Gravel has the greatest permeability in above options. Permeability depends upon size of particles and degree of saturation. Permeability is the measure of the capacity of a body to promote the development of a magnetic field in itself also it is called as a distributed inductance in Transmission Line Theory. Therefore, it is the level of magnetization that a body gets in answer to an applied magnetic field.

A.Gravel

is the correct answer, that was on the mini quiz

b.

explanation:

10.0

d₁ = displacement of tern from arctic to antarctic = 11000 miles

d₂ = displacement of tern from antarctic to arctic =   - 11000 miles

d = total displacement for the journey

total displacement for the journey is given as

d = d₁ + d₂

d = 11000 + (-11000)

d = 0 miles

t₁ = time of travel from arctic to antarctic = 3 months = 3 x 30 days = 90 days

t₂ = time of travel from antarctic to arctic = 3 months = 3 x 30 days = 90 days

t = total time of travel

total time of travel is given as

t = t₁ + t₂

t = 90 + 90

t = 180 days

average velocity is given as

average velocity = total displacement/ total time

v = d/t

v = 0/180

v = 0 miles/day