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Mrac [35]
2 years ago
14

Explain the origin of the magnitude designation for determining the brightness of stars. Why does it seem to go backward, with s

maller numbers indicating brighter stars?
Physics
1 answer:
Mashcka [7]2 years ago
5 0

Answer:

Hipparchus was an ancient Greek who classified stars based on the brightness in 129 B.C. He grouped the brightest stars and ranked them 1 (first magnitude) and dimmest stars as 6 (sixth magnitude). Thus, the smaller numbers indicated brighter stars. Now, the scale extends in negative axis as well. More the negative number, brighter is the star. For example, Sun has magnitude -26.74.

This the apparent magnitude which means the classification is based on the brightness of the star as it appears from the Earth.

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A long coaxial cable (Fig. 2.26) carries a uniform volume charge density rho on the inner cylinder (radius a), and a uniform sur
Yuki888 [10]

Answer:

a) E = ρ / e0

b) E = ρ*a / (e0 * r)

c) E = 0

Explanation:

Because of the geometry, the electric field lines will all have a radial direction.

Using Gauss law

Q/e0 = \int \int E * dA

Using a Gaussian surface that is cylinder concentric to the cable, the side walls will have a flux of zero, because the electric field lines will be perpendicular. The round wall of the cylinder will have the electric field lines normal to it.

We can make this cylinder of different radii to evaluate the electric field at different points.

Then:

A = 2*π*r (area of cylinder per unit of length)

Q/e0 = 2*π*r*E

E = Q / (2*π*e0*r)

Where Q is the charge contained inside the cylinder.

Inside the cable core:

There is a uniform charge density ρ

Q(r) = ρ * 2*π*r

Then

E = ρ * 2*π*r / (2*π*e0*r)

E = ρ / e0 (electric field is constant inside the charged cylinder.

Between ther inner cilinder and the tube:

Q = ρ * 2*π*a

E = ρ * 2*π*a / (2*π*e0*r)

E = ρ*a / (e0 * r)

Outside the tube, the charges of the core cancel each other.

E=0

4 0
2 years ago
A 1.0 kg block is attached to an unstretched
KonstantinChe [14]

Answer:

Change in  potential energy of the block-spring-Earth

system between Figure 1 and Figure 2 = 1 Nm.

Explanation:

Here, spring constant, k  = 50 N/m.

given block comes down eventually 0.2 m below.

here, g = 10 m/s.

let block be at a height h above the ground in figure 1.

⇒In figure 2, potential energy of the block-spring-Earth

system = m×g×(h - 0.2) + 1/2× k × x². where, x = change in spring length.

⇒ Change in  potential energy of the block-spring-Earth

system between Figure 1 and Figure 2 = (m×g×(h - 0.2)) - (1/2× k × x²)

              =  (1×10×0.2) - (1/2×50×0.2×0.2) = 1 Nm.

4 0
2 years ago
What happens to the particles of a liquid when energy is removed from them?
KonstantinChe [14]

Answer:

D: The distance between the particles decreases

Explanation:

Taking away energy slows down molecules, like how you slow down when you are cold (I think)

3 0
2 years ago
In this lab, you will use a falling cylinder attached to a propeller in a water bath to explore the conversion of energy in a sy
Tema [17]

Answer:How is potential energy converted to thermal energy in a system?

Explanation:

3 0
2 years ago
Read 2 more answers
A solid steel column is 4.0 m long and 0.20 m in diameter. Young's modulus for this steel is 2.0 × 1011 N/m2. By what distance d
zzz [600]

Answer:

3.12 x 10^-5 m

Explanation:

Length of steel column, L = 4 m

diameter, d = 0.2 m

radius = half of diameter = 0.1 m

Young's modulus, Y = 2 x 10^11 N/m^2

Mass of truck, m = 5000 kg

Force, F = mass of truck x acceleration due to gravity

F = 5000 x 9.8 = 49000 N

Area of crossection of cable,

A =  \pi r^{2}=3.14\times\0.1\times0.1=0.0314m^{2}

Let ΔL be the shrink in length of cable, then by the formula of Young's modulus

Y=\frac{F\times L}{A\times\Delta L}

\Delta L = \frac{F\times L}{A\times Y}

\Delta L = \frac{49000\times 4}{0.0314\times 2\times10^{11}}

ΔL = 3.12 x 10^-5 m

Thus, the shrink in the length of cable is 3.12 x 10^-5 m.

8 0
2 years ago
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