Most Important Selected Qs for JEE AdvancedPhysicsRotational Motion
A uniform stick of mass 18 kg and length 3 m spins around on a frictionless horizontal plane, with its Centre of Mass stationary. A mass M is placed on the plane, and the stick collides elastically with it, as shown (with the contact point being the end of the stick). What should M (in kg ) be so that after the collision the stick has translational motion, but no rotational motion?
Correct answer
9
Step-by-step solution
(i) L _ i = L _ f ; m l^2 12 = MV l 2 ~V = m l 6 M (ii) P _ i = P _ f ; 0= MV - mV ₁ ~V = mV M l 6 = V ₁ (iii) e =1= V - (- V ₁ ) l 2 -0 ~V + V ₁= l 2 ; m l 6 M + l 6 = l 2 ; ( m M +1 )=3 ~m M =2 M = m 2 =9 ~kg .