When does a star reach equilibrium?

2 answers:

5 0

Actually, that does not happen until the protostar becomes a star when nuclear ignition starts and is maintained. It takes awhile for new star to go through its T-Tauri stage and settle down on the main sequence.

A STAR does not reach hydrostatic equilibrium until it on the main sequence. Otherwise, it would remain a brown dwarf with not enough mass to to maintain nuclear fusion for more than 3,000 to 10,00 years.

Nata [24]2 years ago

4 0

Answer:

The correct answer is when gravity is balanced by the outward force of nuclear fusion hopefully this helps!

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What are the observed effects of sleep deprivation on leptin and ghrelin?

Afina-wow [57]

Answer:

Lack of sleep increases hunger hormone ghrelin and decreases the satiety hormone leptin which may help explain the association between inadequate sleep and overweight.

Explanation:

6 0

3 years ago

Tracie measured 87.47 mg of cholesterol in 0.03 mL of blood. What is the density of this mixture in g/mL?

Lelu [443]

We can use a simple equation to solve this problem.

d = m/v

Where d is the density, m is the mass and v is the volume.

d = ?

m = 87.47 mg = 87.47 x 10⁻³ g

v = 0.03 mL

By applying the equation,

d = 87.47 x 10⁻³ g / 0.03 mL

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3 years ago

Briefly describe bohr's model postulates and its limitations.

ch4aika [34]

Answer:

Bohr's Model postulates-

I postulate - The electrons in an atom orbit around the nucleus in definite circular paths called orbits or shells.

II Postulate - Each shell or orbit represents a specific amount of energy.

III Postulate - By emitting or absorbing energy, an electron may shift from one stationary energy orbit to another.

Three main Limitations -

1- It adjusts to the hydrogen atom's spectrum but not to the spectra of other atoms.

2 - In the definition of the electron as a tiny particle that spins around the atomic nucleus, the wave properties of the electron are not described.

3- Bohr is unable to understand why classical electromagnetism is inapplicable to his model. That is why, when electrons are in a stationary orbit, they do not emit electromagnetic radiation.

Explanation:

About Bohr's postulates-

1 - The electron spins in circling circles around the nucleus, emitting no energy. The orbital angular momentum is constant in these orbits.

Only certain radii of orbits, corresponding to certain given energy levels, are required for electrons in an atom.

2- Not every orbit is possible. However, whenever an electron is in a legal orbit, it is in a state of unique and constant energy and does not emit energy (stationary energy orbit).

For example - The energies allowed for electrons in the hydrogen atom are given by the following equation: The Rydberg constant for the hydrogen atom is $-2.8\times10^-^1^8$ in this equation, and n = quantum number will range from 1 to ∞. For each of the values of n, the electron energies of a hydrogen atom produced by the above equation are negative. As n rises, the energy becomes less negative and thus rises.

3- By emitting or absorbing energy, an electron may shift from one stationary energy orbit to another.

The energy difference between the two states would be equal to the energy released or consumed. This energy E is in the form of a photon, and it can be measured using the following formula:

$E=h$ $v$

E is the energy (absorbed or emitted) in this equation, and h is the Planck constant (its value is $6.63\times10^-^3^4 Js$ ) and v denotes the frequency of light, which is calculated in 1/ s.