Answer: OPTION B

THEY WILL MEET AT CENTRE OF MASS

LET' d ' be the density of spheres,x1 be the distance travelled by the smaller sphere and x2 be the distance travelled by the larger sphere

and they are separated by the distance of 7R

x2= 7R- x1

m1*x1=m2*x2          

d*4/3*3.14*R^3 *x1= D*4/3*3.14*8*R^3 *(7R -x1)

BY SOLVING THIS

x1=56R/9

Explanation:

Answer:

Now,

Here the net force is zero and also the displacement will also be zero.

So we have

 ---------------(i)

and also,

---------------(ii)

-------------------(iii)

Adding equation (iii) and (ii) we get

=>

=>

=>

=>

Hence the distance covered by the smaller body just before the Collison will be 3.5 R ≈ 30/9 R

So I guess it will be option (D)

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