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Ipatiy [6.2K]
3 years ago
14

Which of the following is not a way that astronomers can find how much dark matter there is in cluster of galaxies?

Physics
1 answer:
Tpy6a [65]3 years ago
6 0

Answer:

<em>b. Observe the radio waves coming from all dark matter; from the strength of the radio waves from each cluster, estimate the amount of dark matter needed to produce them.</em>

<em></em>

Explanation:

The universe is thought to be made up of 85% dark matters. <em>Dark matter is called dark because it does not appear to interact with the electromagnetic field, which means it doesn't absorb, reflect or emit electromagnetic radiation, and is therefore difficult to detect. This means that option b is wrong since radio wave is an electromagnetic wave</em>. Dark matter is a form of matter that makes up  about a quarter of the total mass–energy density of the universe. Dark matter was theorized due a variety of astrophysical observations and gravitational effects that cannot be explained by accepted theories of gravity unless there were more matter in the universe than can be seen.

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Future space rockets might propel themselves by firing laser beams, rather than exhaust gases, out the back. The acceleration wo
Nina [5.8K]

Answer:

Acceleration = 0.0282 m/s^2

Distance = 13.98 * 10^12 m

Explanation:

we will apply the energy theorem

work done = ΔK.E ( change in Kinetic energy )  ---- ( 1 )

<em>where :</em>

work done = p * t

                  = 15 * 10^6 watts * ( 1 year ) = 473040000 * 10^6 J

( note : convert 1 year to seconds )

and ΔK.E = 1/2 mVf^2   given ; m = 1200 kg  and initial V = 0

<u>back to equation 1 </u>

473040000 * 10^6  = 1/2 mv^2

Vf^2 = 2(473040000 * 10^6 ) / 1200

∴ Vf = 887918.92 m/s

<u>i) Determine how fast the rocket is ( acceleration of the rocket )</u>

a = Vf / t

  = 887918.92 / ( 1 year )

  = 0.0282 m/s^2

<u>ii) determine distance travelled by rocket </u>

Vf^2 - Vi^2 = 2as

Vi = 0

hence ; Vf^2 = 2as

s ( distance ) =  Vf^2 / ( 2a )

                     = ( 887918.92 )^2 / ( 2 * 0.0282 )

                    = 13.98 * 10^12 m

8 0
3 years ago
How large a force is necessary to stretch a 4.0-mm-diameter steel wire from its original length by 1.0%?
jekas [21]

The force needed to stretch the steel wire by 1% is 25,140 N.

The given parameters include;

  • diameter of the steel, d = 4 mm
  • the radius of the wire, r = 2mm = 0.002 m
  • original length of the wire, L₁
  • final length of the wire, L₂ = 1.01 x L₁ (increase of 1% = 101%)
  • extension of the wire e = L₂ - L₁ = 1.01L₁ - L₁ = 0.01L₁
  • the Youngs modulus of steel, E = 200 Gpa

The area of the steel wire is calculated as follows;

A = \pi r^2\\\\ A= 3.142 \times (0.002)^2\\\\ A= 1.257 \times 10^{-5} \ m^2

The force needed to stretch the wire is calculated from Youngs modulus of elasticity given as;

E = \frac{stress}{strain} = \frac{F/A}{e/L} = \frac{FL}{Ae} \\\\F = \frac{EAe}{L}

F = \frac{200 \times 10^9\  \times\  1.257\times 10^{-5}\  \times \ 0.01l_1}{l_1} \\\\F = 25,140\ N

Thus, the force needed to stretch the steel wire by 1% is 25,140 N.

Learn more here: brainly.com/question/21413915

4 0
2 years ago
A 62 kg box is lifted 12 meters off the ground. How much work was done?
OleMash [197]

7291.2 I hope this is right


6 0
3 years ago
Read 2 more answers
Which illustration represent the substance at a higher temperature? Explain.
mamaluj [8]

The addition of heat energy to a system always causes the temperature of that system to increase. This is always true because you are adding heat of a substance to increase  its temperature. For example, you are going to drink a cup of coffee. And you wanted it hot to boost your attention. So you have to use hot water. In order for your water to become hot or warm, you need boil it in a kettle. Note that you are going to use an electric stove. The electric stove gets it energy from the source giving it a hotter temperature to the water in the kettle. You are applying heat energy to warm the water. So, the statement is true.

7 0
3 years ago
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How do you change current in a circuit without changing the voltage?
Sunny_sXe [5.5K]

Decrease the reactance is the correct answer i believe

Explanation:

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3 years ago
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