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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.

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Two identical trucks have mass 5100 kg when empty, and the maximum permissible load for each is 8000 kg. the first truck, carryi
Oksanka [162]
<span>The 2nd truck was overloaded with a load of 16833 kg instead of the permissible load of 8000 kg. The key here is the conservation of momentum. For the first truck, the momentum is 0(5100 + 4300) The second truck has a starting momentum of 60(5100 + x) And finally, after the collision, the momentum of the whole system is 42(5100 + 4300 + 5100 + x) So let's set the equations for before and after the collision equal to each other. 0(5100 + 4300) + 60(5100 + x) = 42(5100 + 4300 + 5100 + x) And solve for x, first by adding the constant terms 0(5100 + 4300) + 60(5100 + x) = 42(14500 + x) Getting rid of the zero term 60(5100 + x) = 42(14500 + x) Distribute the 60 and the 42. 60*5100 + 60x = 42*14500 + 42x 306000 + 60x = 609000 + 42x Subtract 42x from both sides 306000 + 18x = 609000 Subtract 306000 from both sides 18x = 303000 And divide both sides by 18 x = 16833.33 So we have the 2nd truck with a load of 16833.33 kg, which is well over it's maximum permissible load of 8000 kg. Let's verify the results by plugging that mass into the before and after collision momentums. 60(5100 + 16833.33) = 60(21933.33) = 1316000 42(5100 + 4300 + 5100 + 16833.33) = 42(31333.33) = 1316000 They match. The 2nd truck was definitely over loaded.</span>
6 0
3 years ago
Which of the following is true about resistivity of any given metal? depends on its temperature. varies nearly linearly with tem
ElenaW [278]

Explanation:

C one is the correct one according to me

4 0
2 years ago
A 4300-N force from a car's engines produces an acceleration of 3.3 m/s2. What is the mass of the car?
sertanlavr [38]

Answer:The net force acting on the car is 3×103 Newtons

Explanation:

5 0
2 years ago
An object is located 50 cm from a converging lens having a focal length of 15 cm. Which of the following is true regarding the i
crimeas [40]

Answer:

It is real, inverted, and smaller than the object.

Explanation:

Let's start by using the lens equation to find the location of the image:

\frac{1}{q}=\frac{1}{f}-\frac{1}{p}

where we have:

q = ? is the distance of the image from the lens

f = 15 cm is the focal length (positive for a converging lens)

p = 50 cm is the distance of the object from the lens

Solving the equation for q, we find

\frac{1}{q}=\frac{1}{15 cm}-\frac{1}{50 cm}=0.047 cm^{-1}

q=\frac{1}{0.047 cm^{-1}}=+21.3 cm

The sign of q is positive, so the image is real.

Now let's also write the magnification equation:

h_i = - h_o \frac{q}{p}

where  

h_i, h_o are the size of the image and of the object

By substituting p = 50 cm and q = 21.3 cm, we find

h_i = - h_o \frac{21.3 cm}{50 cm}=-0.43 h_o

So we notice that:

|h_i| < |h_o| : this means that the image is smaller than the object

h_i < 0 : this means that the image is inverted

so, the correct option is:

It is real, inverted, and smaller than the object.

7 0
3 years ago
2. A particular planet has a moment of inertia of 9.74 × 1037 kg•m2 and a mass of 5.98 × 1024 kg. Based on these values, what is
mash [69]

Answer:

6.38\cdot 10^6 m

Explanation:

The planet can be thought as a solid sphere rotating around its axis. The moment of inertia of a solid sphere rotating arount the axis is

I=\frac{2}{5}MR^2

where

M is the mass

R is the radius

For the planet in the problem, we have

M=5.98\cdot 10^{24} kg

I=9.74\cdot 10^{37} kg\cdot m^2

Solving the equation for R, we find the radius of the planet:

R=\sqrt{\frac{5I}{2M}}=\sqrt{\frac{5(9.74\cdot 10^{37}}{2(5.98\cdot 10^{24}}}=6.38\cdot 10^6 m

3 0
3 years ago
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