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schepotkina [342]
3 years ago
8

A star has a declination of approximately 45°. Which of these statements is correct about the star?

Physics
1 answer:
bonufazy [111]3 years ago
6 0

The star is approximately 45° above the celestial equator.  <em>(A)</em>

"Declination" on the celestial coordinate system is equivalent to latitude on the terrestrial one.

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قوة الجذب المركزي تكون في اتجاه
pochemuha

Answer:

تكون دائمًا متعامدة مع سرعة الجسم وتكون دائمًا في اتجاه مركز انحناء المسار

Explanation:

6 0
3 years ago
Read 2 more answers
How much thermal energy is required to raise the temperature of 5 kg of water 50℃? The specific heat of water is 4168 J/kg*C.
sasho [114]

Answer/solution:

Given :

Mass =5kg

T 1 =20 C,T 2  =100 ∘C

ΔT=100−20=80 ∘C

Q=m×C×ΔT

where C= specific heat capacity of water

=4200J/(kgK)

Q=5×4200×80

=1680000 Joule.

=1680KJ

3 0
2 years ago
Pure silicon contains approximately 1.0 X 1016 free electrons per cubic meter. (
Margarita [4]
A. The formula for mean free time is:

t = V/(4π√2 r²vN)
where
N = 1×10¹⁶ molecules (per m³)
V = 1 m³
r = 111×10⁻⁷m (atomic radius of silicon)

Let's solve for v first:
v = √(3RT/M) = √(3(8.314 m³·Pa/mol·K)(25 + 273 K)/28.1 g/mol Si)
v = 16.26 m/s

t = (1 m³)/(4π√2 (111×10⁻⁷m)²(16.26 m/s)(1×10¹⁶ molecules))
<em>t = 2.81×10⁻9 s</em>

<em>Pure silicon has a high resistivity relative to copper because copper is a conductor, while silicon is a semi-conductor. </em>
3 0
3 years ago
A 100.0 gram sample of Polonium-210 is contained for 552 days. How many half-lives occur during this period of time, if the half
Leto [7]

Answer:

4 half-lives will occur during this period of time.

Explanation:

Formula used :

a_o=a\times e^{-\lambda t}

\lambda =\frac{0.693}{t_{1/2}}

a=\frac{a_o}{2^n}

where,

a = amount of reactant left after n-half lives and time t

a_o = Initial amount of the reactant.

\lambda = decay constant

t_{1\2} = half life of an isotope

n = number of half lives

We have :

a_o=100.0 g

a = ?

t = 552 days

t_{1/2}=138 days

a=100.0 g\times e^{-\frac{0.693}{138}\times 552}

a=6.254 g

6.254 g=\frac{100.0 g}{2^n}

2^n=\frac{100.0 g}{6.254 g}

n = 4

4 half-lives will occur during this period of time.

4 0
3 years ago
How does radiation differ from conduction? (4 points)
mario62 [17]
The difference between radiation and conduction is that radiation is described as he transfer of heat energy by electromagnetic waves without involving particles. Conduction is described as the flow of heat from one solid to another, using a hot knife as an example.
7 0
3 years ago
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