Please help with this AP Physics 1 problem

i) kinetic friction; ii) The friction force always acts in the opposite direction to the movement of the surface where friction exists.

Explanation:

Part i )

At that time the type of friction that exists is kinetic, as there is movement by the wheel. At the moment when the wheel remains in rest over the inclined plane, the friction force which would be used will be the static force.

Part ii)

The friction force always acts in the opposite direction to the movement of the surface where friction exists. It is not opposed to the sense of movement. In order for the wheel to rise on the inclined plane, it must turn to the right, that is to say in the clockwise direction, therefore the friction force must go in the opposite direction to the rotation of the wheel, that is to say, go in the opposite direction to the movement of the surface under friction effect, that is why it points in the same direction of displacement of the wheel.

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