1. The problem statement, all variables and given/known data a rifle with a barell length of 60 cm fires a 10g bullet with a horizontal speed of 400 m/s. the bullet strikes a block of wood and penetrates to a depth of 12 cm. how long does it take the bullet to come to rest( from when it penetrates the block to when it stops)? 2. Relevant equations kinematic equations 3. The attempt at a solution we can figure out the acceleration of the bullet while its in the block with Vf2= Vi2 + 2aX which gives -6.7*105 but now when i try to use X= Vit + 1/2 at2 to figure out time it give me a function with no real roots what am i doing wrong here?