Physics, 21.04.2020 17:46 vperez5765

) Diameter of a star: Assume that the temperature of the Sun is 5800K and the temperature of Sirius A is 10,000K. If the luminosity of Sirius A is 23 times that of the Sun, calculate the radius of Sirius A relative to the Sun. Sirius A is times the size of the Sun. Your answer should be a number in the format (x. x).

Answers: 2

Show answers

Answers

Answer from: bigred89

Sirius A is 1.608 times the size of the Sun.

Explanation:

The radiant flux establishes how much energy an observer or a detector can get from a luminous source per unit time and per unit surface area.

$R_{p} = \frac{L}{4\pi r^2}$ (1)

Where $R_{p}$ is the radiant power received from the source, L is its intrinsic luminosity and r is the distance.

The Stefan-Boltzmann law is defined as:

$R_{p} = \sigma \cdot T^{4}$ (2)

Where $R_{p}$ is the radiant power, $\sigma$ is the Stefan-Boltzmann constant and T is the temperature.

Then, equation 2 can be replaced in equation 1

$\sigma \cdot T^{4} = \frac{L}{4\pi r^2}$ (3)

Notice that L is the energy emitted per second by the source.

Therefore, r can be isolated from equation 3.

$r^2 = \frac{L}{4\pi \sigma\cdot T^{4}}$

$r = \sqrt{\frac{L}{4\pi \sigma\cdot T^{4}}}$ (4)

The luminosity of the Sun can be estimated isolating L from equation 3.

$L = (4\pi r^2)(\sigma \cdot T^{4})$

but, $r = 696.34x10^{6}m$ and T = 5800K

$L_{Sun} = 4\pi (696.34x10^{6}m)^2(5.67x10^{-8} W/m^{2} K^{4} )(5800K)^{4})$

$L = 3.90x10^{26} W$

To find the luminosity of Sirius A, the following can be used:

$\frac{L_{SiriusA}}{L_{sun}} = 23$

${L_{SiriusA}} = (3.90x10^{26} W)(23)$

${L_{SiriusA}} = 8.97x10^{27}W$

Finally, equation 4 can be used to determine the radius of Sirius A.

$r = \sqrt{\frac{8.97x10^{27}W}{4\pi (5.67x10^{-8} W/m^{2} K^{4})(10000K)^{4}}}$

$r = 1.12x10^{9}m$

So, Sirius A has a radius of $1.12x10^{9}m$

$\frac{1.12x10^{9}m}{696.34x10^{6}m} = 1608$

Hence, Sirius A is 1.608 times the size of the Sun.

Answer from: Quest

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

$f\alpha \frac{dp}{dt}$

⇒ $f= k \frac{dp}{dt}$

here k is the proportionality constant whose value is 1.

$f=\frac{dp}{dt}$

$f= \frac{d[mv]}{dt}$

$f= m\frac{dv}{dt} +v\frac{dm}{dt}$

$f=ma+v\frac{dm}{dt}$ [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

Answer from: Quest

not too sure thinking all accelerations are pointed down

Other questions on the subject: Physics

Physics, 22.06.2019 10:00, starsinopoli13

How are the crust and the inner core alike? a) they are both solid. b) they both have the same temperature. c) they are both under the same pressure. d) they are both very close to the center of the earth.

Answers: 1

continue

Physics, 22.06.2019 11:30, alexandroperez13

With the simplified model of the eye, what corrective lens (specified by focal length as measured in air) would be needed to enable a person underwater to focus an infinitely distant object? (be careful-the focal length of a lens underwater is not the same as in air! assume that the corrective lens has a refractive index of 1.62 and that the lens is used in eyeglasses, not goggles, so there is water on both sides of the lens. assume that the eyeglasses are 1.90

Answers: 1

continue

Physics, 22.06.2019 12:30, shotocaffe

What is the power rating of the lightbulb if 3.0 a flow through it when connected to a 15 v battery

Answers: 1

continue

Physics, 22.06.2019 18:30, july00

En un laboratorio, nakisha mezcla una solución de hidróxido de sodio con un indicador llamado fenolftaleína. cuando se combinan, crean una solución de color rosa. nakisha se pregunta si la mezcla de otras soluciones con fenolftaleína también creará este color rosa. ? cómo podría nakisha utilizar el proceso de investigación científica para determinar si la mezcla de otras soluciones con fenolftaleína también creará un color rosa? marque las que correspondan.

Answers: 2

continue

You know the right answer?

) Diameter of a star: Assume that the temperature of the Sun is 5800K and the temperature of Sirius...