a boat ended up with a velocity of 30.m/s [N30.E] after it experienced an acceleration of 3.0m/s^2 [S] for a period of 4.0s what displacement did the boat cover

  96 m

Explanation:

The average velocity over those 4 seconds is the velocity after 2 seconds:

  30 m/s -(2 s)(3.0 m/s^2) = 24 m/s

The displacement is the product of this average velocity and the duration of the acceleration:

  d = (24 m/s)(4 s) = 96 m

The boat covered 96 m while being accelerated.

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