A river flows from south to north at 5.6 km/hr. On the west bank of this river, a boat launches and travels perpendicular to the current with a velocity of 7.7 km/hr due east. If the river is 1.6 km wide at this point, how far downstream does the boat land on the east bank of the river relative to the point it started at on the west bank?

Downstream displacement = 1.1648 km

Explanation:

Given:

Speed of flow = 5.6 km/h

Speed of current upstream = 7.7 km/h

Increase in size = 1.6 km wide

Computation:

Total time to cross = Increase in size / Speed of current upstream

Total time to cross = 1.6 / 7.7

Total time to cross = 0.208 h

Downstream displacement = Speed of flow × Total time to cross

Downstream displacement = 5.6 × 0.208

Downstream displacement = 1.1648 km

asthenosphere and convection

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