Answer:
D) hot stars and interstellar gas, particularly hydrogen
Explanation:
Emission nebula is the nebula which is formed of the ionized gases which emit light of different wavelengths. The common source of ionization of the emission nebula is high-energy photons mostly which are emitted from hot star present nearby to it.
<u>The emission nebulae include H II regions. An H II region is the region of the interstellar atomic hydrogen which is ionized. It is the cloud of the partially ionized gas in which star formation takes place.</u>
Answer:
the girl's displacement in both magnitude and direction is 7.81 m at 50.2⁰ North west.
Explanation:
Given;
6km due west, and
5km due north
The magnitude of her displacement is calculated by forming a right angled triangle. The hypotenuse side of the triangle is the girl's displacement.
d² = 5² + 6²
d² = 25 + 36
d² = 61
d = √61
d = 7.81 m
The direction of the girl is calculated as;

Therefore, the girl's displacement in both magnitude and direction is 7.81 m at 50.2⁰ North west.
Newton's Laws<span>. </span>Kepler's Laws<span> are wonderful as a description of the </span>motions<span> of the </span>planets<span>. However, they provide no explanation of why the </span>planets<span> move in this way. Moreover, </span>Kepler's<span> Third </span>Law<span> only works for </span>planets<span> around the Sun and does not apply to the Moon's orbit around the Earth or the moons of Jupiter.
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Answer:
the number of grains in the ball is 274,848
Explanation:
Given that;
diameter = 0.5 mm
so radius r = 0.25 mm
first we determine the volume of the ball using the following equation;
V = 4/3×πr³
we substitute
V = 4/3×π(0.25)³
V = 0.06544 mm³
Now form table 1.1 "Grain sizes" a metal with grain size number of 12 has about 4,200,000 grains/mm³
so;
Number of grains N = 0.06544 × 4,200,000
N = 274,848 grains
Therefore, the number of grains in the ball is 274,848