Answer:
Explanation:
1 ) 
 Put v2,i =0, in second equation 
v2,f= (m2-m1)v2,i + 2m1v1,i/m1+m2
v2,f = 0 + 2m1v1,i/m1+m2
v2,f =  2m1v1,i/m1+m2
In this equation coefficient of v1,i is positive so v2,f and v1,i have the same sign.
2 )
Put m1 < m2  and v2,i =0 in first equation
v1,f= (m1-m2)v1,i + 2m2v2,1/m1+m2
v1,f= (m1-m2)v1,i 
As m1-m2 is negative , v1f and v1i will have opposite sign.
3 )
Put m1 > m2  and v2,i =0 in first equation
v1,f= (m1-m2)v1,i + 2m2v2,1/m1+m2
v1,f= (m1-m2)v1,i 
m1 - m2 is positive so v1f and v1i will have same  sign.
4 )
Put m1 = m2 and v2,i =0 in first equation
v1,f= (m1-m2)v1,i 
= 0 because m1 = m2 
So glider 1 will stop because v1,f = 0 .