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STD 11 - 4.2 friction — JEE STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceJEESTD 11 - 4.2 friction4 Marks
MCQ
A roller coaster is designed such that riders experience "weightlessness" as they go round the top of a hill whose radius of curvature is $20\, m.$ The speed of the car at the top of the hill is between
  • A
    $16\ m/s$  and $ 17\  m/s $ 
  • B
    $13\  m/s$  and $14\  m/s$ 
  • C
    $14\ m/s$  and $15\  m/s$ 
  • D
    $15\  m/s$  and $ 16\  m/s$ 
✓

Answer

$mg = \frac{{m{v^2}}}{R} $
$\Rightarrow v = \sqrt {Rg}$
$v = \sqrt {20 \times 10} $
$= \sqrt {200} $
$= 14.1\ m/s$
i.e,. Between $14 $ and $15\ m/s.$

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