Assume that there is a constant ratio between stellar mass and light in the disks of spiral galaxies, and that disks have a constant surface brightness. use the scaling with radius r, of the stellar mass within such a radius, and the scaling of circular velocity, vc, with enclosed mass (ignoring dark matter), to "explain" the tully–fisher relation, l ? vc4. the fourth-power dependence is indeed what is observed at infrared wavelengths, at which light traces stellar mass relatively well. in reality, however, dark matter cannot be ignored, and spiral disks do not have a constant surface brightness.

radiation warms things up temp rises convection currents air circ windy weather

answer; equivalent to a one(1) horsepower motor;

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

the only real purpose of sputnik 1 was to beat the us into space. we were getting close to launching a useful satellite, explorer 1 - which launched on january 31, 1958. the ussr had to beat that, so they launched sputnik 1 on october 4, 19