Question

derermine the average force necessary to stop a bullet of mass 20g and speed 250M/S as it penetrates wood to a distance 12.5cm

Answer 1

whole kinetic energy will be loss in work done against bullet to stop it K.E=F*S

Answer 2

v2=u2+2as  v=o'  u=250m/s  s=12.5cm/100m.put the valu of               a=-25*10^4  so  F=ma  =-20/1000*25*10^4 =-8*10^-8N