The mass of a star can be determined by studying ___.
2 answers:
Answer: C. Binary star systems
Let’s see your options:
a) The <em>color of the star</em>: the color is not used in calculating the mass of a star, because it has no relation to it. Think about a red supergiant and a red dwarf: they have the same color, but they are completely different stars, with respectively a big and a small mass.
b) <em>Kepler’s laws</em>: these laws can be applied in what is called the “approximation of 1 body”, which means that is assumed that one body has a much bigger mass than the other and can be considered at rest. This is the case of a star-planet system and the mass that can be calculated is that of the planet.
c)<em> Binary star systems</em>: these are the only cases in which is possible the direct measure of the mass of the stars. Binary systems are classified as follows:
- Visual binaries: each star can be resolved and the motion around the center of mass can be measured.
- Astrometric binaries: only one star is visible, but the presence of the companion can be inferred by the movement of the first star around the system’s center of mass.
- Eclipse binaries: the two stars are not resolved (separated), but the luminosity varies periodically when one star eclipses the other.
- Spectroscopic binaries: the two stars are not resolved, but their spectrum reveals that they are a binary system.
In all these cases we have a “two-body problem” that can be solved by changing system of reference: the motion of bodies 1 and 2 is equivalent to the motion of a body of mass equal to the system’s reduced mass
moving in the potential generated by the total mass (M1 + M2) considered at rest. Hence, we can determine the masses of the two stars.
Let’s see your options:
a) The <em>color of the star</em>: the color is not used in calculating the mass of a star, because it has no relation to it. Think about a red supergiant and a red dwarf: they have the same color, but they are completely different stars, with respectively a big and a small mass.
b) <em>Kepler’s laws</em>: these laws can be applied in what is called the “approximation of 1 body”, which means that is assumed that one body has a much bigger mass than the other and can be considered at rest. This is the case of a star-planet system and the mass that can be calculated is that of the planet.
c)<em> Binary star systems</em>: these are the only cases in which is possible the direct measure of the mass of the stars. Binary systems are classified as follows:
- Visual binaries: each star can be resolved and the motion around the center of mass can be measured.
- Astrometric binaries: only one star is visible, but the presence of the companion can be inferred by the movement of the first star around the system’s center of mass.
- Eclipse binaries: the two stars are not resolved (separated), but the luminosity varies periodically when one star eclipses the other.
- Spectroscopic binaries: the two stars are not resolved, but their spectrum reveals that they are a binary system.
In all these cases we have a “two-body problem” that can be solved by changing system of reference: the motion of bodies 1 and 2 is equivalent to the motion of a body of mass equal to the system’s reduced mass
You might be interested in
Answer:
<em> B) The voltage on dry skin needs to be 200 times larger than the voltage on wet skin.</em>
<em></em>
Explanation:
This is the complete question
A person will feel a shock when a current of greater than approximately 100μ A flows between his index finger and thumb. If the resistance of dry skin is 200 times larger than the resistance of wet skin, how do the maximum voltages without shock compare in each scenario?
A) The voltage on dry skin needs to be 200 times smaller than the voltage on wet skin.
B) The voltage on dry skin needs to be 200 times larger than the voltage on wet skin.
C) The voltage on dry skin is the same as the voltage on wet skin.
D) The voltage on dry skin needs to be 40,000 times larger than the voltage on wet skin.
Ohm's law states that electric current is proportional to voltage and inversely proportional to resistance.
the equation is written as
V = IR
Where V is the voltage
I is the current
R is the resistance
for this case, the current I is 100μ A = 100 x 10^16 A
resistance of wet skin = R
resistance of dry skin = 200R
for the wet skin, voltage will be
V = IR =
for dry skin, voltage will be
V = IR =
Comparing both voltages
÷
= 200
<em>this means that the voltage on the wet skin should be 200 times lesser than the voltage on the dry skin or the voltage on the dry skin should be 200 times more than the voltage on the wet skin.</em>
Explanation:
We have,
Semimajor axis is
It is required to find the orbital period of a dwarf planet. Let T is time period. The relation between the time period and the semi major axis is given by Kepler's third law. Its mathematical form is given by :
G is universal gravitational constant
M is solar mass
Plugging all the values,
Since,
So, the orbital period of a dwarf planet is 138.52 years.