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3.2 , motion in plane — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysics3.2 , motion in plane1 Mark
MCQ
A person running horizontally observes that rain is falling on his head vertically with speed $10\,m/s$. He stops and observes that rain is coming at an angle $30^o$ with vertical. Find the speed of rain w.r.t. ground
  • A
    $20\,m/s$
  • ✓
    $\frac{{20}}{{\sqrt 3 }}m/s$
  • C
    $10\sqrt 3\,m/s$
  • D
    $\frac{{10}}{{\sqrt 3 }}m/s$
✓

Answer

Correct option: B.
$\frac{{20}}{{\sqrt 3 }}m/s$
b
Given $\mathrm{V}_{\mathrm{r}} \cos 30^{\circ}=10 \mathrm{m} / \mathrm{s}$

$\mathrm{V}_{\mathrm{r}}=\frac{20}{\sqrt{3}} \mathrm{m} / \mathrm{s}$

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