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3 years ago

8

A certain very bright star has an effective surface temperature of 20 000 K. Assuming that it radiates as a blackbody, what is t

he wavelength at which () is maximum?

1 answer:

algol [13]3 years ago

4 0

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An element's atomic number is 7. How many electrons would an atom of this element have?

almond37 [142]

Hey There!

The atomic number represents the electrons and protons, therefore, if the atomic number of the element is 7 then there are 7 electrons and protons in the element.

In order to determine the amount of neutrons, you would subtract the atomic number from the atomic mass.

Hope this helped!

5 0

4 years ago

1. What is the kinetic Energy of a 1500kg object moving at 21 m/s?

Wewaii [24]

The formula for working out kinetic energy is

=122

KE = kinetic energy
m = mass of a body
v = velocity of a body

kinetic energy (KE) is equal to half of an object's mass (1/2*m) multiplied by the velocity squared. For example, if a an object with a mass of 10 kg (m = 10 kg) is moving at a velocity of 5 meters per second (v = 5 m/s), the kinetic energy is equal to 125 Joules, or (1/2 * 10 kg) * 5 m/s2.

For the first one I think :
Answer:
KE = 330750 J

I’m not sure about the second one- sorry

The third is
Answer:
KE = 41454 J

Hope it helps and it is correct, sorry if it isn’t !

8 0

3 years ago

A mercury barometer reads 745.0 mm on the roof of a building and 760.0 mm on the ground. Assuming a constant value of 1.29 kg/m3

Ipatiy [6.2K]

Answer:

The height of the building is 158.140 meters.

Explanation:

A barometer is system that helps measuring atmospheric pressure. Manometric pressure is the difference between total and atmospheric pressures. Manometric pressure difference is directly proportional to fluid density and height difference. That is:

$\Delta P \propto \rho \cdot \Delta h$

$\Delta P = k \cdot \rho \cdot \Delta h$

Where:

$\Delta P$ - Manometric pressure difference, measured in kilopascals.

$\rho$ - Fluid density, measured in kilograms per cubic meter.

$\Delta h$ - Height difference, measured in meters.

Now, an equivalent height difference with a different fluid can be found by eliminating manometric pressure and proportionality constant:

$\rho_{air} \cdot \Delta h_{air} = \rho_{Hg} \cdot \Delta h_{Hg}$

$\Delta h_{air} = \frac{\rho_{Hg}}{\rho_{air}} \cdot \Delta h_{Hg}$

Where:

$\Delta h_{air}$ - Height difference of the air column, measured in meters.

$\Delta h_{Hg}$ - Height difference of the mercury column, measured in meters.

$\rho_{air}$ - Density of air, measured in kilograms per cubic meter.

$\rho_{Hg}$ - Density of mercury, measured in kilograms per cubic meter.

If $\Delta h_{Hg} = 0.015\,m$ , $\rho_{air} = 1.29\,\frac{kg}{m^{3}}$ and $\rho_{Hg} = 13600\,\frac{kg}{m^{3}}$ , the height difference of the air column is:

$\Delta h_{air} = \frac{13600\,\frac{kg}{m^{3}} }{1.29\,\frac{kg}{m^{3}} }\times (0.015\,m)$

$\Delta h_{air} = 158.140\,m$

The height of the building is 158.140 meters.

5 0

3 years ago

Read 2 more answers

An astronaut in an inertial reference frame measures a time interval Δt between her heartbeats. What will observers in all other

Reika [66]

Answer:

It will be more than deta t

Explanation:

Because

deta t' = န deta t

But န= 1/√ (1 - v²/c²

So the observers in all the initial frames will be more than deta t

3 0

4 years ago

Match the description with the type of front

Inga [223]

Answer: Do you need help with how to get the photograph?

Explanation:It's in the comments if you want to known have a good day!

:)

4 0

3 years ago