Answer:
27 blocks
Explanation:
First, the expression to use here is the following:
P = F/A
Where:
P: pressure
F: Force exerted
A: Area of the block.
Now , we need to know the number of blocks needed to exert a pressure that equals at least 2 atm. To know this, we should rewrite the equation. We know that certain number of blocks, with the same weight and dimensions are putting one after one over the first block, so we can say that:
P = W/A
P = n * W1 / A
n would be the number of blocks, and W1 the weight of the block.We have all the data, and we need to calculate the area of the block which is:
A = 0.2 * 0.1 = 0.02 m²
Solving now for n:
n = P * A / W1
The pressure has to be expressed in N/m²
P = 2 atm * 1.01x10^5 N/m² atm = 2.02x10^5 N/m²
Finally, replacing all data we have:
n = 2.02x10^5 * 0.02 / 150
n = 26.93
We can round this result to 27. So the minimum number of blocks is 27.
The emissivity of the earth is 0.5
The emissivity of the earth is calculated by the Stefan's law
To solve this problem it is necessary to apply the concept related to root mean square velocity, which can be expressed as
Where,
T = Temperature
R = Gas ideal constant
n = Number of moles in grams.
Our values are given as
The temperature is
Therefore the root mean square velocity would be
The fraction of velocity then can be calculated between the escape velocity and the root mean square velocity
Therefore the fraction of the scape velocity on the earth for molecula hydrogen is 0.1736
