How does inertia affect a person who is not wearing a seatbelt during a collision?

The result of inertia due to failure to wear a seatbelt will result in the passenger becoming a projectile. The weight of the passenger and the speed of travel prior to the collision will be multiplied together to equal the force their body will endure. For example, the force a person will be subjected to for a passenger weighing 100 pounds, in a vehicle traveling at 60 mph, will be the equivalent of 6000 pounds (3 tons) hitting a brick wall.

Due to collision, vehicle of the person stops but he continue to do sobecause of inertia...he can't stop himself so he his accident without seatbelt in that case is definite