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3 years ago

A. Write 2 -3 sentences describing the big bang theory and explaining why it is considered a theory, as opposed to a hypothesis.

2 answers:

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A. In the beginning there was a singularity with indefinite mass and density. It's a theory cause there are facts such as galaxies moving away from each other that can prove it.

b) Anywhere at any point of the Universe there is some radiation called background radiation. It led to conclude that the universe was hotter and much denser many many years ago.

c) Model of the universe can be defined by the value of the cosmological constant, so now it is considered to be flat. It probably means that it will expand forever.

jekas [21]3 years ago

6 0

Answer:

a. Big Bang Theory explains the beginning of the universe. The entire matter of the universe is believed to be concentrated in a single point. This point had infinite density. At time, t = 0, at the big bang, universe started expanding and cooling down. This theory is most widely accepted theory describing the beginning of the universe. It is not considered as hypothesis because of the evidences received by the scientists- detection of cosmic microwave background, red shift of the light received from the galaxies indicating that universe is expanding.

b. Cosmic Microwave background radiation is a faint radiation having average temperature of 3 K detected every where around from the sky. This is a residual radiation from 400,000 years after the beginning of the universe. The universe was very hot and dense at the beginning and thus, opaque. Hence, detection of the CMB has provided the evidence of Big bang theory.

c. Scientists have proposed three models of the universe:

1. closed universe- The universe has finite volume and curves around itself. The space-time has positive curvature.

2. open universe - The universe has infinite volume and has a negative curvature.

3. flat universe - The universe has zero curvature. It has infinite volume. The actual density of the universe is equal to the critical density of the universe. The expansion rate slows down over time. This is the most widely accepted model.

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1 year ago

Read 2 more answers

A loop of wire is in a magnetic field such that its axis is parallel with the field direction. Which of the following would resu

ahrayia [7]

Answer:

All the given options will result in an induced emf in the loop.

Explanation:

The induced emf in a conductor is directly proportional to the rate of change of flux.

$emf = -\frac{d \phi}{dt} \\\\where;\\\\\phi \ is \ magnetic \ flux\\\\\phi = BA\ cos \theta$

where;

A is the area of the loop

B is the strength of the magnetic field

θ is the angle between the loop and the magnetic field

<em>Considering option </em><em>A</em>, moving the loop outside the magnetic field will change the strength of the magnetic field and consequently result in an induced emf.

<em>Considering option </em><em>B</em>, a change in diameter of the loop, will cause a change in the magnetic flux and in turn result in an induced emf.

Option C has a similar effect with option A, thus both will result in an induced emf.

Finally, <em>considering option</em> D, spinning the loop such that its axis does not consistently line up with the magnetic field direction will<em> </em>change the angle<em> </em>between the loop and the magnetic field. This effect will also result in an induced emf.

Therefore, all the given options will result in an induced emf in the loop.

4 0

2 years ago

A street light is mounted at the top of a 15-ft-tall pole. A man 6 ft tall walks away from the pole with a speed of 4 ft/s along

babymother [125]

Answer:

Explanation:

height of pole = 15 ft

height of man = 6 ft

Let the length of shadow is y .

According to the diagram

Let at any time the distance of man is x.

The two triangles are similar

$\frac{y-x}{y}=\frac{6}{15}$

15 y - 15 x = 6 y

9 y = 15 x

$y=\frac{5}{3}x$

Differentiate with respect to time.

$\frac{dy}{dt}=\frac{5}{3}\frac{dx}{dt}$

As given, dx/dt = 4 ft/s

$\frac{dy}{dt}=\frac{5}{3}\times 4$

$\frac{dy}{dt}=\frac{20}{3}$ ft/s

6 0

3 years ago

A 1.80-m string of weight 0.0126 N is tied to the ceiling at its upper end, and the lower end supports a weight W. Neglect the v

Veseljchak [2.6K]

Answer:

W = 0.135 N

Explanation:

Given:

- y (x, t) = 8.50*cos(172*x -2730*t)

- Weight of string m*g = 0.0126 N

- Attached weight = W

Find:

The attached weight W given that Tension and W are equal.

Solution:

The general form of standing mechanical waves is given by:

y (x, t) = A*cos(k*x -w*t)

Where k = stiffness and w = angular frequency

Hence,

k = 172 and w = 2730

- Calculate wave speed V:

V = w / k = 2730 / 172 = 13.78 m/s

- Tension in the string T:

T = Y*V^2

where Y: is the mass per unit length of the string.

- The tension T and weight attached W are equal:

T = W = Y*V^2 = (w/L*g)*V^2

W = (0.0126 / 1.8*9.81)*(13.78)^2

W = 0.135 N

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3 years ago

2. How did Isabella discover capoeira?

Nataliya [291]

Answer:

she saw it in a movie

Explanation:

she said her mom and her saw it in Step up 3 and fell in love

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2 years ago