Answer:
Explanation:
The direction of force will be in upward direction making an angle of θ with the vertical .
Reaction force R = mg - F cosθ
Friction force = μR
= .36 (mg - F cosθ )
Horizontal component of applied force
= F sinθ
For equilibrium
F sinθ = .36 (mg - F cosθ)
F sinθ + .36 F cosθ =.36 mg
F (sinθ + .36 cosθ) = .36 mg
F R( cosδsinθ +sinδ cosθ) = .36 mg ( Rcosδ = 1 . Rsinδ= .36 )
F R sin( θ+δ ) = . 36 mg
F = .36 mg / Rsin( θ+δ )
For minimum F , sin( θ+δ ) should be maximum
sin( θ+ δ ) = sin 90
θ+ δ = 90
Rsinδ / Rcosδ = .36
δ = 20⁰
θ = 70⁰ Ans
