Mr.verma (50 kg) and mr.mathur(60 kg) are sitting on the two ends of 4m boat of mass 40 kg standing still in water.To duscuss the mechanics of the problem they come to the middle of the boat.Neglecting friction with water, how far does the boat move on the water dsuring the process

pls explain the stategy to deal center of mass problems.

http://goiit.com/chapters/tutorial/physics/center_mass.htm

  stategy ??

there is no external force.. and they were initially at rest..,

so their center of mass remains at rest.. 

bas itna hi karna hai..

concept involved in this question is that the CM does not move.

earpit, yeh stategy to mujhe bhi pata hai.mujhe application chahiya.Agar bas itna hi karna hai to solution bhi karke de do.I will be grateful to u.

HERE LET THE DISTANCE TRAVELLED BY  BOAT = x

SO mass of Mr mathur = 60kg  

displacement with respect to boat = 2m,  D (with respect to ground) = (x - 2)

now mass of Mr verma = 50kg  

displacement with respect to boat  = 2m( in opp direction)  ,D (with respect to ground) =(2+x)

SO CENTRE OF MASS (SHIFT) = 0

SO

M = mass of boat = 40kg

so

so x = 0.13m in direction of Mr verma

BEST OF LUCK

thank u abhi