Calculating the density parameter (Cosmology)

AI Thread Summary
The discussion focuses on calculating the density parameter in cosmology using the provided data: z=0.04, m=17.38, and σ=0.19. The density parameter is defined as the ratio of the current density (p0) to the critical density (pc). The participant expresses uncertainty about how to proceed due to insufficient information to determine the current density of the universe. They seek assistance in solving the problem. The conversation also includes a brief expression of frustration about the lack of responses.
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Homework Statement



Decide the density parameter from the following data:

z=0.04, m= 17.38 and σ=0.19

Homework Equations



Definition of the density parameter:

2ry0bgw.png


Where p0 is the current density and pc is the critical density.

The Attempt at a Solution



I feel like I don't have enough information to calculate it as I'm unable to calculate the current density of the universe. Any help is greatly appreciated! Thanks.
 
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Two pictures of an attempt at a solution (no units)>

ab2yyt.png


and

qpos3d.png
 
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Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
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Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
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