why do we believe 90 percent of the mass of the milky way is in the form of dark matter?

Answers

Answer 1

Answer:

The orbital speeds of stars far from the galactic center are surprisingly high, suggesting that these stars are feeling gravitational effects from unseen matter in the halo.


Related Questions

A guitar string has a fundamental frequency f. The tension in the string is increased by 1.70%. Ignoring the very small stretch of the string. How does the fundamental frequency change?

Answers

The characteristics of the speed of the waves in strings and the resonance allows to find the change in the fundamental frequency when changing the tension is:

 The change in fundamental frequency is: f = 1.08 f₀

The speed of the chord wave is given by the relationship between the tension and the density of the medium.

          [tex]v= \sqrt{\frac{T}{\mu } }[/tex]  

Where v is the velocity of the wave, T the tension of the string and μ the density

In a rope held at the ends, a process of standing waves occurs, two at the point where it is attached we have a node and a anti-node in the center.

             2L = n λ

Where L is the length of the chord and call the wavelength

Wave speeds are related to wavelength and frequency.

        v = λ f

We substitute.

            [tex]\sqrt{\frac{T}{\mu } } = \frac{2L}{n} \ \ f[/tex]  

For the fundamental frequency n = 1

            f₀ = [tex]f_o = \sqrt{\frac{T}{\mu } } \ \ \frac{1}{2L}[/tex]  

They indicate that the tension increases 1.70%

           T = T₀ + 0.17 T₀

           T = 1.17 T₀

We substitute.

         [tex]f = \sqrt{1.17 } \ \sqrt{\frac{T_o}{\mu } } \ \ \frac{1}{2L}[/tex]

         f = ra1.17 f₀

         f = 1.08 f₀

In conclusion, using the characteristics of the velocity of the waves in strings and the resonance we can find the change in the fundamental frequency when changing the tension is:

 The change in fundamental frequency is: f = 1.08 f₀

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An "energy bar" contains 26 ggof carbohydrates.How much energy is this in joules?

Answers

I’m it’s about 3.4878 energy in joules

Where could light travel the easiest and fastest?

A) through air
B) through empty space
C) through liquid hydrogen

Answers

Explanation:

Light travels fastest through air

Answer:

try through air

Explanation:

. Quỹ đạo chuyển động của một vật là

Answers

Answer:

you are very kind Po lang

How does water temperature affect density?

Answers

it expands, increasing in volume. The warmer the water, the more space it takes up, and the lower its density.

A crane lifts a 10000 N load through a distance of 30mins in 40s calculate work done

Answers

Given,

Force = 10,000 N

Distance = 30 m

Time = 40 s

Work done = force × distance

Work = 10,000 × 30

Work = 300,000 J

______

꧁✿ ᴿᴬᴵᴺᴮᴼᵂˢᴬᴸᵀ2222 ✬꧂

The work done on the object is equal to the power it experiences which is equal to 735 watts.

What is work done?

Work done is defined as the product of force applied and the distance over which the force is applied on the object. Work is done on an object when a force is applied to an object and the object is moved through a particular distance.

The time rate of doing work is called as power, which is designated by the symbol P. It is measured in the units of watts, where one watt is equal to one joule energy applied per second time.

Work done on an object is equal to the force (F) multiplied by the distance d in the direction of the force. Where, time interval is Δt.

P = W/Δt = F × d/Δt = m × g × h/Δt = 100 × 9.8 × 30 / 40

Power = 735 watts

The power of the object is 735 watts.

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What symbols are these?

Answers

Answer:

the bottom one is wollsiegel

Tommy does 45 Joules of work to push the pencil over 3 meter. How much force did he use?

Answers

Answer:

Work = Force × Distance

Therefore Force = Work/Distance

= 45 joules/3 metres

= 15 newton

Explanation:

Answer:

15

Explanation:

15

2. What are the challenges of wind energy that causes decrease in the electrical production?
3. Give two solutions:
1. Modification in the structure of the turbine
2. Modification in the function of the turbine.

4. You must estimate the cost in each solution, and which one is more affordable and efficient for the municipality to go for.

5. You must make sure that there is minimal energy loss.

Answers

Levelized production cost is a big challenge in the production of wind energy.

The main challenge in the production of wind energy is the high production cost. It has to minimize the Levelized Production Cost (LPC) which is the ratio between energy production cost and economic lifetime. This problem can be solved by doing modification in the structure of the turbine as well as we must ensure minimal energy loss.

The modification in the structure can produce more electrical energy and reduce the energy loss also provides more profit to the company so we can conclude that levelized production cost is a big challenge in the production of wind energy.

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A bob attached to a string of length L = 1.25 m, initially found at the equilibrium
position, is given an initial velocity v = 0.8 m/s. The maximum displacement angle,
Omax, is: (Take g=10 m/s)
17
3.2
13
10.2
6.4
Clear selection
A hoh attached to a string of length 2 m is displaced by an angle of 8º and then

Answers

The maximum displacement angle of the bob is 13⁰.

The given parameters;

Length of the pendulum, L = 1.25 mInitial velocity of the bob, v = 0.8 m/s

The maximum displacement of the bob is calculated by applying the principle of conservation of energy;

[tex]P.E = K.E\\\\mgh = \frac{1}{2} mv^2\\\\h = \frac{v^2}{2g} \\\\h = \frac{0.8^2}{2\times 10} \\\\h = 0.032 \ m[/tex]

The maximum displacement angle is calculated as follows;

[tex]cos \theta = \frac{L-h}{L} \\\\cos \theta = \frac{1.25 - 0.032}{1.25} \\\\\cos \theta = \frac{1.218}{1.25} \\\\cos \theta = 0.9744\\\\\theta = cos^{-1}(0.9744)\\\\\theta = 13\ ^0[/tex]

Thus, the maximum displacement angle of the bob is 13⁰.

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You throw a can of cranberry sauce straight up in the air with an initial velocity of 12 m/s. What is the maximum height the baseball reaches above your head.

Answers

Answer:

Δx=7.35m

Explanation:

This is a free fall problem (g= -9.8 m/s²).

Displacement: ? <--- what you're trying to find (max height)

Initial Velocity: 12 m/s

Final Velocity: 0 m/s <-- since the can will land back in your hands

Time: Missing <-- not needed to solve

Acceleration: -9.8 m/s²

The equation that you will use is vf²=vi²+2aΔx

Now plug the information into the equation!

(0m/s)²=(12m/s)²+2(-9.8m/s²)Δx

Multiply the 2 with the acceleration (-9.8m/s²)

(0m/s)²=(12m/s)²-19.6m/s²Δx

Now you need to square the final and initial velocity

0m/s=144m/s-19.6m/s²Δx

Move 144 to the other side of the equal sign

-144m/s=-19.6m/s²Δx

Divide both sides by -19.6m/s²

7.346m=Δx

You can round it to the tenth or hundreth place, up to you!

For this example, I'll round to the hundredth...

Δx=7.35m

I would double check this answer or review it yourself to see if it's correct.

Good luck with your studies!

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