In a ballistics test, a 25.0 g bullet traveling horizontally at 1100 m/s goes through a 30.0 cm-thick 450 kg stationary target and emerges with a speed of 900 m/s. The target is free to slide on a smooth horizontal surface. How long is the bullet in the target? i tried to use this equation : t = d/v_avg 900-1100 / 2 = -100 = vavg .3=-100 t t= .003 but it is saying that it is incorrect. can someone tell me what i am doing wrong?