Arrange the following stars in order of their evolution:
a star with no nuclear reactions going on in the core, which is made primarily of carbon and oxygen.
a star of uniform composition from center to surface; it contains hydrogen but has no nuclear reactions going on in the core.
a star that is fusing hydrogen to form helium in its core.
a star that is fusing helium to carbon in the core and hydrogen to helium in a shell around the core.
a star that has no nuclear reactions going on in the core but is fusing hydrogen to form helium in a shell around the core.

1. A star of uniform composition from center to surface; it contains hydrogen but has no nuclear reactions going on in the core.

2. A star that is fusing hydrogen to form helium in its core.

3. A star that has no nuclear reactions going on in the core but is fusing hydrogen to form helium in a shell around the core.

4. A star that is fusing helium to carbon in the core and hydrogen to helium in a shell around the core.

5. A star with no nuclear reactions going on in the core, which is made primarily of carbon and oxygen.

positive reinforcement? ?

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