Let a = acceleration of runner 2 = constant
Let v1 = speed of runner 1 = 10.3 m/s
Let v2 = speed of runner 2
Let v2o = speed of runner 2 at halfway point
Let x1o= 0 = position of runner 1 at time =0
Let x2o = -2 = position of runner 2 at time =0
Since v1 is constant x1= tv1
Since runner 2 is accelerating uniformly, v2=at+v2o and x2=x2o+.5at2+v2ot+x2o
Let T = time at end of race and x2 > x1 for runner 2 to win
Set x1=100 to find t = T= 100/10.3
Set x2=100 and solve for a