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JEE Main 202126 FebruaryEvening Shift
Exam
JEE Main
Year
2021
Date
26 February
Shift
Evening Shift
Subject
Physics
Chapter
Laws of Motion

JEE Main 2021 · 26 February · Evening Shift · Physics · Laws of Motion

An inclined plane making an angle of 30 ° with the horizontal is...

An inclined plane making an angle of 30°30 ° with the horizontal is placed in a uniform horizontal electric field 200NC200\dfrac{N}{C} as shown in the figure. A body of mass 1kgandcharge1kg and charge5mCisallowedtoslidedownfromrestataheightofis allowed to slide down from rest at a height of1m.Ifthecoefficientoffrictionis. If the coefficient of friction is0 . 2,findthetimetakenbythebodytoreachthebottom.<br/>[g=9.8ms−2;sin⁡30°=12;cos⁡30°=32]find the time taken by the body to reach the bottom.<br />\left[g = 9 . 8m{s}^{- 2}; \sin 30 ° = \dfrac{1}{2}; \cos 30 ° = \dfrac{\sqrt{3}}{2}\right]

An inclined plane making an angle of 30 ° with the horizontal is placed in a uniform horizontal electric field

Options

  1. A0.92s0 . 92s
  2. B1.3s1 . 3s
  3. C0.46s0 . 46s
  4. D2.3s2 . 3s

Correct answer

B. 1.3s1 . 3s

Step-by-step solution

An inclined plane making an angle of 30 ° with the horizontal is placed in a uniform horizontal electric field

here N=9.8cos⁡30+1sin⁡30≈9NN = 9 . 8\cos 30 + 1\sin 30 \approx 9N

soa=9.8sin⁡30−1cos⁡30−\muN1a = \dfrac{9 . 8\sin 30 - 1\cos 30 - \muN}{1}

a=2.233ms−2a = 2 . 233m{s}^{- 2}

By S=ut+12at2S = ut + \dfrac{1}{2}a{t}^{2}

=12(2.233)t2= \dfrac{1}{2}\left(2 . 233\right){t}^{2}

sin⁡30°\sin 30 °

t≈1.3sect \approx 1 . 3sec

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