Answer:
Explanation:
Initial angular velocity ω₀ = 151 x 2π / 60
= 15.8 rad /s
final velocity = 0
Angular deceleration α = 2.23 rad / s
ω² = ω₀² - 2 α θ
0 = 15.8² - 2 x 2.23 θ
= 55.99 rad
one revolution = 2π radian
55.99 radian = 55.99 / 2 π no of terns
= 9 approx .
Answer:
37.8 m
Explanation:
At point 0, the ball is at height y₀.
At point 1, the ball is at height 30 m.
At point 2, the ball is at height 0 m.
Given:
y₁ = 30 m
y₂ = 0 m
v₀ = 0 m/s
a = -10 m/s²
t₂ − t₁ = 1.5 s
Find: y₀
Use constant acceleration equation.
y = y₀ + v₀ t + ½ at²
Evaluate at point 1.
y₁ = y₀ + v₀ t₁ + ½ at₁²
30 m = y₀ + (0 m/s) t₁ + ½ (-10 m/s²) t₁²
30 = y₀ − 5t₁²
Evaluate at point 2.
y₂ = y₀ + v₀ t₂ + ½ at₂²
0 m = y₀ + (0 m/s) t₂ + ½ (-10 m/s²) t₂²
0 = y₀ − 5t₂²
y₀ = 5t₂²
Substitute:
y₀ = 5 (1.5 + t₁)²
y₀ = 5 (2.25 + 3t₁ + t₁²)
y₀ = 11.25 + 15t₁ + 5t₁²
30 = 11.25 + 15t₁ + 5t₁² − 5t₁²
30 = 11.25 + 15t₁
t₁ = 1.25
30 = y₀ − 5t₁²
30 = y₀ − 5(1.25)²
y₀ ≈ 37.8
If the Earth's axis were 'straight' ... pefectly perpendicular to the ecliptic
plane ... then:
-- Day and night would be the same length ... every day of the year,
everywhere on Earth !
-- There wouldn't be any seasons, anywhere. There might still be some
'weather' ... cloudy days, sunny days, occasional rain, wind etc. But
there would be no average change during the year. No hot months or
cold months. In any one place, the weather would always be generally
the same, every day, all year. Everywhere all around the equator would be
generally the hottest on Earth, and the local climates would generally get
cooler as you moved away from the equator and toward the poles.
Answer:
1. Main Sequence - middle life 17
2. red
3. blue
4. White dwarf stars are much hotter than Red Supergiants 15. List the color of the stars from hottest to coldest: Blue, White, Yellow, Orange, Red 16.
5. red giants
Explanation:
Main sequence stars have a Morgan-Keenan luminosity class labeled V. red giant and supergiant stars (luminosity classes I through III) occupy the region above the main sequence. They have low surface temperatures and high luminosities which, according to the Stefan-Boltzmann law, means they also have large radii. White dwarf stars are much hotter than Red Supergiants 15. List the color of the stars from hottest to coldest: Blue, White, Yellow, Orange, Red 16. The hottest stars are the blue stars. A star appears blue once its surface temperature gets above 10,000 Kelvin, or so, a star will appear blue to our eyes. The lowest temperature stars are red while the hottest stars are blue. Astronomers are able to measure the temperatures of the surfaces of stars by comparing their spectra to the spectrum of a black body. Most stars, including the sun, are "main sequence stars," fueled by nuclear fusion converting hydrogen into helium. ...
As stars begin to die, they become giants and supergiants (above the main sequence).
