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JEE Main 20207 JanuaryEvening Shift
Exam
JEE Main
Year
2020
Date
7 January
Shift
Evening Shift
Subject
Physics
Chapter
Laws of Motion

JEE Main 2020 · 7 January · Evening Shift · Physics · Laws of Motion

A mass of 10kg is suspended by a rope of length 4m , from the...

A mass of 10kg10kg is suspended by a rope of length 4m4m, from the ceiling. A force FF is applied horizontally at the mid-point of the rope such that the top half of the rope makes an angle of 45°45 ° with the vertical. Then FF equals: (Take g=10ms−2g = 10m{s}^{- 2} and the rope to be massless)

Options

  1. A100N100N
  2. B90N90N
  3. C70N70N
  4. D75N75N

Correct answer

A. 100N100N

Step-by-step solution

Let the tension in the string is TT.

Applying the condition of equilibrium in the vertical direction,

Tcos\left(45 °\right) = 100</p><p></p><p>⇒ \dfrac{T}{\sqrt{2}} = 100 . . . \left(1\right)</p><p>Inthehorizontaldirection,</p><p>Tsin(45°)=F</p><p>In the horizontal direction,</p><p>Tsin\left(45 °\right) = F

⇒T2=F⇒ \dfrac{T}{\sqrt{2}} = F

Put the value of TT from equation \left(1\right),</p><p>,</p><p>⇒ F = 100N</p><p>So,thehorizontalforceappliedontheropewillbe</p><p>So, the horizontal force applied on the rope will be100N$.

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