Q: A bullet fired from a gun is more dangerous than an air molecule hitting a person , though both of them have almost same speed . Why ?
Ans: As we know that mass of bullet is much greater than the mass of an air molecule . Due to greater mass of bullet and almost same speed of air molecule , the linear momentum of bullet is much larger than the linear momentum of an air molecule . Hence force required to stop a bullet will be much larger than the force required to stop an air molecule . That is why a bullet fired from a gun is more dangerous than an air molecule .