1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
abruzzese [7]
3 years ago
7

Consider a spherical volume of space that is large enough to be considered homogeneous. Also consider a particle on the surface

of this volume that is moving away from the center with the Hubble flow. Assuming that the pressure within the volume is negligible, the universe will re-collapse if the particle's Hubble speed is: A. Greater than its escape speed from the mass within the volume B. The same as its escape speed from the mass within the volume C. Less than its escape speed from the mass within the volume
Physics
1 answer:
LenKa [72]3 years ago
3 0

Answer:

Option A applies.

A.  Greater than its escape speed from the mass within the volume

Explanation:

Here it is mentioned that the spherical volume is large enough for the space to be considered as homogeneous. Also, the pressure within the volume is negligible, so that will not result into the re collapse of the Universe. Now as per our knowing, Hubble's Law relates the average speed of the particle to the distance R between the Earth and the particle. So, if the particle's speed is greater than it's escape speed from the mass within the volume, then the Universe is bound to re collapse back again. Option A applies.

You might be interested in
A ship is travelling due east at 30 km/hr and a boy runs across the deck
dsp73

Answer:

Vr = 20 [km/h]

Explanation:

In order to solve this problem, we have to add the relative velocities. We must remember that velocity is a vector, therefore it has magnitude and direction. We will take the sea as the reference measurement level.

Let's take the direction of the ship as positive. Therefore the boy moves in the opposite direction (Negative) to the reference level (the sea).

V_{r}=30-10\\V_{r}=20 [km/h]

8 0
3 years ago
Air contained in a rigid, insulated tank fitted with a paddle wheel, initially at 300 K, 2 bar, and a volume of 3 m3, is stirred
madam [21]

Answer:

a)P₂ =4 bar

b)W= - 1482.48 KJ

It means that work done on the system.

c)S₂ - S₁ = 3.42 KJ/K

Explanation:

Given that

T₁ = 300 K   ,V₁ = 3 m³  ,P₁=2 bar

T₂ = 600 K ,V₂=V₁ 3 m³

Given that tank is rigid and insulated.It means that volume of the gas will remain constant.

Lets take the final pressure = P₂

For ideal gas  P V = m R T

\dfrac{P_2}{P_1}=\dfrac{T_2}{T_1}

P_2=\dfrac{T_2}{T_1}\times P_1

P_2=\dfrac{600}{300}\times 2

P₂ =4 bar

Internal energy

ΔU = m Cv ΔT

Cv=0.71 KJ/kg.k for air

m=\dfrac{PV}{RT}

m=\dfrac{200\times 3}{0.287\times 300}\ kg

m= 6.96 kg

ΔU= 6.96 x 0.71 x (600 - 300)

ΔU=1482.48 KJ

From first law

Q= ΔU + W

Q= 0  Insulated

W = - ΔU

W= - 1482.48 KJ

It means that work done on the system.

Change in the entropy

S_2-S_1=mC_v\ \ln\dfrac{T_2}{T_1}

S_2-S_1=6.96\times 0.71\ \ln\dfrac{600}{300}

S₂ - S₁ = 3.42 KJ/K

 

5 0
3 years ago
How much force is needed to accelerate a 68 kilogram skier at a rate of 1.2m/sec
xxMikexx [17]

Let's use Newton's 2nd law of motion:

                                     Force = (mass) x (acceleration)

                                     Force = (68 kg) x (1.2 m/s²) =  81.6 newtons .

8 0
3 years ago
Read 2 more answers
The part of a sound wave in which the particles are most spread out is called a(n)
Nutka1998 [239]
Seismic wave is the answer
7 0
3 years ago
Examples of energy balance: physical education
mart [117]

Answer:children burn calories to being a student  

Explanation:That mean when a children getting ready to go to high school

7 0
3 years ago
Other questions:
  • Explain in your own words the interaction between the electric and magnetic fields that make up a light wave.
    6·1 answer
  • The molar mass of a gas
    7·2 answers
  • During exercise stored chemical energy is convorted to energy that can be used for ?
    14·2 answers
  • How many centimeters are there in a length 676 inches?
    14·1 answer
  • Does gender affect your aerobic capacity?
    8·1 answer
  • An astronaut of mass m in a spacecraft experiences a gravitational force F=mg when stationary on the launchpad.
    15·1 answer
  • The brightness of a star depends on its (color, composition of atmosphere, or distance from earth), and stars that are closer lo
    12·2 answers
  • Photosynthesis is an endothermic chemical reaction that forms sugars from carbon dioxide, water, and the sun's energy. Which of
    13·2 answers
  • A(n) ______ is a gap in the geologic record where some rock layers have been lot because of erosion
    15·1 answer
  • A thermometer has its term marked millimeter instead of degree celcuis .The lower fixed point is 30mm and upper fixed point is 1
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!