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Fluid Mechanics — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsFluid Mechanics1 Mark
Question
Consider the equations

$\text{P}=\lim_\limits{\triangle\text{s}\rightarrow0}\frac{\text{F}}{\triangle\text{s}}$ and $\text{P}_1-\text{P}_2-\text{pgz}$

In an elevator accelerating upward.

  1. Both the equations are valid.
  2. The first is valid but not the second.
  3. The second is valid but not the first.
  4. Both are invalid.
✓

Answer

  1. The first is valid but not the second.

For a point inside the elevator, pressure can be defined as $\text{P}=\lim_\limits{\triangle\text{s}\rightarrow0}\frac{\text{F}}{\triangle\text{s}}\cdot$ It is independent of the acceleration of the elevator.
The modified form of the second equation, which will be valid in the given case, is given.$\text{P}_1-\text{P}_2=\text{p}(\text{g}+\text{a}_0)\text{z}$
Here, acceleration a0(say) due to elevator accelerating upwards is also taken into account.

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