a bullet fired into a target loses half its velocity after penetrating 25cm.How much further will it penetrate before coming to rest ?

Answer 1

Kinetic energy, KE = (1/2)mv²
resistive force = constant

Retaining half the velocity means (1/2)^2=1/4 of the kinetic energy.

Since 50% of the KE penetrates 25 cm, so
25% of the (remaining) KE penetrates 12.5 cm.

Answer 2

Good