A tennis ball is thrown vertically upward with an initial velocity of +8.0 m/s.
a. What will the ball's speed be when it returns to its
starting point?
b. How long will the ball take to reach its starting
point?

i think the answer is a, hope this is right, that would be my best guess.

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

find the sum of the two horizontal vectors and the sum of the two vertical vectors

isoceles right angled triangle

answerdmitry mendeleyev made a workable classification of the elements