Question

A particle a has charge +q and a particle b has charge +4q with each of them having the same mass m

Answer 1

Ka/Kb=q×v/4q×v =1/2mVa^2/1/2mVb^2 Va^2/Vb^2=1/4 Va/VB=1/2 or Va:Vb=1:2 It is the ratio between the kinectic energies between the two particles.