Physics Circle home Student Login

Home›Chapters›Rotational Motion PYQs›Torque, Couple & Equilibrium of Rigid Bodies›Question 47

NEET 1998 (AIPMT) · Torque, Couple & Equilibrium of Rigid Bodies

Torque, Couple & Equilibrium of Rigid Bodies question from NEET 1998 (AIPMT)

Q47NEET 1998 · AIPMTMedium

Torque, Couple & Equilibrium of Rigid Bodies

OO is the centre of an equilateral triangle ABC. F1, F2ABC.\ F_1,\ F_2 and F3F_3 are three forces acting along the sides AB, BCAB,\ BC and ACAC as shown in figure. What should be the magnitude of F3F_3 so that the total torque about OO is zero?

Figure

Show answer and solution

Answer: (c)

  1. O is the incentre, so every side is at the same distance r from O and each torque is F⋅rF\cdot r.
  2. F1F_1 along AB and F2F_2 along BC both give anticlockwise torque about O; F3F_3 along AC gives clockwise torque.
  3. F3r=(F1+F2)r⇒F3=F1+F2F_3 r = (F_1 + F_2) r \Rightarrow F_3 = F_1 + F_2
  4. So the answer is (c).
Report a mistake

More questions on Torque, Couple & Equilibrium of Rigid Bodies