Một quả cầu, bán kính 20 cm, tích điện đều với điện
tích tổng cộng là 6.10– 6 C.
Tính mật độ điện tích khối
của quả cầu.

d. air pressure decreases as altitude increases.

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

0.93xc=0.93x3x10^8m/s

2.54cm is 1 inch

360seconds i 1 hr