MHT CET 2025 23rd April Morning Shift | Fluid Mechanics Question 1 | Physics

A disc of paper of radius ' $R$ ' has a hole of radius ' $r$ '. It is floating on a liquid of surface tension ' T '. The force of surface tension on the disc is

$2 \pi \mathrm{~T}(\mathrm{R}-\mathrm{r})$

$2 \pi \mathrm{~T}(\mathrm{R}+\mathrm{r})$

$3 \pi \mathrm{TR}$

$4 \pi \mathrm{~T}(\mathrm{R}+\mathrm{r})$

MHT CET 2025 23rd April Morning Shift

MCQ (Single Correct Answer)

-0

A wind with speed $50 \mathrm{~m} / \mathrm{s}$ blows parallel to the roof of a house. The area of the roof is $300 \mathrm{~m}^2$. Assume that the pressure inside the house is atmospheric pressure. Density of air is $1.2 \mathrm{~kg} / \mathrm{m}^3$. The magnitude of the force exerted by the wind on the roof will be

$1.5 \times 10^5 \mathrm{~N}$

$3.0 \times 10^5 \mathrm{~N}$

$4.5 \times 10^5 \mathrm{~N}$

$9.0 \times 10^5 \mathrm{~N}$

MHT CET 2025 22nd April Evening Shift

MCQ (Single Correct Answer)

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The energy needed for breaking a liquid drop of radius ' $R$ ' into ' $n$ ' droplets each of radius ' $r$ ' is $[\mathrm{T}=$ surface tension of the liquid]

$\quad 4 \pi \mathrm{TR}^2\left[\frac{\mathrm{R}}{\mathrm{r}}+1\right]$

$\quad 4 \pi \mathrm{TR}^2\left[\frac{\mathrm{R}}{\mathrm{r}}-1\right]$

$\quad 4 \pi \mathrm{TR}^2\left[\frac{\mathrm{r}}{\mathrm{R}}+1\right]$

$\quad 4 \pi \operatorname{Tr}^2\left[\frac{\mathrm{R}}{\mathrm{r}}-1\right]$

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