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bezimeni [28]
3 years ago
7

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

Physics
2 answers:
Gemiola [76]3 years ago
7 0

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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A 65-kg ice skater stands facing a wall with his arms bent and then pushes away from the wall by straightening his arms. At the
Marrrta [24]

Our values can be defined like this,

m = 65kg

v = 3.5m / s

d = 0.55m

The problem can be solved for part A, through the Work Theorem that says the following,

W = \Delta KE

Where

KE = Kinetic energy,

Given things like that and replacing we have that the work is given by

W = Fd

and kinetic energy by

\frac {1} {2} mv ^ 2

So,

Fd = \frac {1} {2} m ^ 2

Clearing F,

F = \frac {mv ^ 2} {2d}

Replacing the values

F = \frac {(65) (3.5)} {2 * 0.55}

F = 723.9N

B) The work done by the wall is zero since there was no displacement of the wall, that is d = 0.

6 0
2 years ago
Bob is coming toward you at a speed of 75 km/hr. You throw a baseball in his direction at 75 km/hr. What does he see the ball do
KengaRu [80]

Answer:

He sees the ball coming at him at 150 km/hr.

Explanation:

In Newtonian physics, the observer would say that the velocity of the first object is the sum of the two velocities.

Due to the same direction, both velocities will be added.

4 0
3 years ago
Read 2 more answers
What’s the Answer for 5-8?
Dafna1 [17]

6. B. 4 electrons

7. Carbon is in everything and it's a compound that all organisms need

8. D. 3

9. Nitrogen gas is almost 80% of the atmosphere

10. Diatomic molecules compose 2 atoms

3 0
3 years ago
0. A 3.00-kg block is dropped from rest on a vertical spring whose spring constant is 750 N/m. The block hits the spring, compre
Dmitry_Shevchenko [17]

Answer:

the spring compressed is 0.1878 m

Explanation:

Given data

mass = 3 kg

spring constant k = 750 N/m

vertical distance h = 0.45

to find out

How far is the spring compressed

solution

we will apply here law of mass of conservation

i.e

gravitational potential energy loss = gain of eastic potential energy of spring

so we say m×g×h = 1/2× k × e²

so e² = 2×m×g×h / k

so

we put all value here

e² = 2×m×g×h / k

e² = 2×3×9.81×0.45 / 750

e²  = 0.0353

e = 0.1878 m

so the spring compressed is 0.1878 m

5 0
3 years ago
A frictionless piston–cylinder device contains 7 kg of nitrogen at 100 kPa and 250 K. Nitrogen is now compressed slowly accordin
lora16 [44]

Answer: -1038.8 kJ

Explanation:

From the question, we can see that PV^n = constant. And as such, we can deduce that it is a polytropic process. Thus, we can use the polytropic work equation to calculate the needed work input.

from the question we were given

Mass of nitrogen, m = 7kg

initial temperature, T1 = 250k

Final temperature, T2 = 450k

Polytropic index, n = 1.4

Specific gas constant, R = 0.2968kJ/kgK

W = [p2 * v2 - p1 * v1] / 1 - n

W = [m * R * T2 - T1] / 1 - n

W = 7*0.2968*(450 - 250)] / 1 - 1.4

W = [7*0.2968*200] / -0.4

W = 415.52 / -0.4

W = -1038.8 kJ

5 0
2 years ago
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