If a body loses half of its velocity on penetrating 3 cm in a wooden block, then how much will it penetrate more before coming to rest?

Assuming the resistance force or retardation to be  constant.v22=v2-2as1                   …(i)      0=v22-2as2                    …(ii)Solving these two equations, we gets2=s13=33=1 cm     (Given, s1 = 3 cm)