Q6 / 181 · NTA Abhyas (JEE Main) 2020 · Physics · Laws of Motion

The minimum force required to move a body up an inclined plane is three times the minimum force required to prevent it from sliding down the plane. If the coefficient of friction between the body and the inclined plane is 123, then the angle of the inclined plane is

  • A
    60°
  • B
    45°
  • Correct answer
    C
    30°
  • D
    15°

Solution

Minimum force required to move a body up a rough inclined plane,
F1=mg(sin⁡θ+μcos⁡θ)

Minimum force required to prevent the body from sliding down the rough inclined plane,
F2=mgsin⁡θ-μcos⁡θ

According to the question,
F1=3F2
mgsin⁡θ+μcos⁡θ=3mgsin⁡θ-μmgcos⁡θ
4μcos⁡θ=2sin⁡θ
sin⁡θ=2μcos⁡θ
tan⁡θ=2μ=13
θ=30°

Hence, the correct answer is option: 'C'.

More Laws of Motion Questions