The position vectors of three particles of mass m_(1)=1kg,m_(2)=2kg and m_(3)=4kg are vecr_(1)=(hati+4hatj+hatk)m,vecr_(2)=(hati+hatj+hatk)m, and vecr_(3)=(2hati-hatj-2hatk)m respectively. Find the position vector of their centre of mass.

The position vectors of three particles of mass m_(1)=1kg,m_(2)=2kg an

1.	The position vectors of three particles of mass m_(1)=1kg,m_(2)=2kg and m_(3)=4kg are vecr_(1)=(hati+4hatj+hatk)m,vecr_(2)=(hati+hatj+hatk)m, and vecr_(3)=(2hati-hatj-2hatk)m respectively. Find the position vector of their centre of mass.
Answer» SOLUTION :The position VECTOR of centre of mass of the three PARTICLES is given by `vecr_(C)=(m_(1)vecr_(1)+m_(2)vecr_(2)+m_(3)vecr_(3))/(m_(1)+m_(2)+m_(3))` `vecr_(c)=(1(hati+4hatj+hatk)+2(hati+hatj+hatk)+4(2hati-hatj-2hatk))/(1+2+4)` `=((11hati+2hatj-5hatk))/(7)=(1)/(7)(11hati+2hatj-5hatk)m`