Q.

Two identical bodies A and B of equal masses have initial velocities v→1=4i^ m/s and v→2=4j^ m/s respectively. The body A has acceleration a→1=6i^+6j^ m/s2 while the acceleration of the other body B is zero. The centre of mass of the two bodies moves in ______ path.                [2026]

1 circular  
2 parabolic  
3 straight line  
4 elliptical  

Ans.

(3)

v→cm=m1v→1+m2v→2m1+m2=m(4i^)+m(4j^)2m=(2i^+2j^) m/s

a→cm=m1a→1+m2a→2m1+m2=m(6i^+6j^)+m(0)2m=3i^+3j^

v→cm and a→cm are along same line so path is a straight line.