Physics, 08.04.2020 04:34 zarrialamons16

If you are lying down and stand up quickly, you can get dizzy or feel faint. This is because the blood vessels don't have time to expand to compensate for the blood pressure drop. If your brain is 0.4 m higher than your heart when you are standing, how much lower is your blood pressure at your brain than it is at your heart

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Answer from: jadynsantiago

Complete Question

If you are lying down and stand up quickly, you can get dizzy or feel faint. This is because the blood vessels don’t have time to expand to compensate for the blood pressure drop. If your brain is 0.4 m higher than your heart when you are standing, how much lower is your blood pressure at your brain than it is at your heart? The density of blood plasma is about 1025 kg/m3 and a typical maximum (systolic) pressure of the blood at the heart is 120 mm of Hg (= 0.16 atm = 16 kP = 1.6 × 104 N/m2).

The pressure at the brain is $P_b = 89.872 \ mm \ of \ Hg$

Explanation:

Generally is mathematically denoted as

$P = \rho gh$

Substituting 1025 kg/m^3 for $\rho$ (the density) , 9.8 m/s^2 for g (acceleration due to gravity) , 0.4m for h (the height )

We have that the pressure difference between the heart and the brain is

P = 1025 * 9.8 *0.4

= 4018 N/m^2

But the pressure of blood at the heart is given as

P_h=120 mm of Hg = 120 * 133 = 1.59*10^3Pa

Now the pressure at the brain is mathematically evaluated as

P_b = P_h - P

= 1.596*10^4 - 4018

= 11982 N/m^2

$P_b= \frac{11982}{133} = 89.872 \ mm \ of \ Hg$

Answer from: Quest

less than one you can't create energy

Answer from: Quest

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia

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If you are lying down and stand up quickly, you can get dizzy or feel faint. This is because the blo...