Question

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

Answer 1

1. during a collision, the person not wearing a seatbelt is already in motion. there is no outside force (the seatbelt) to stop this motion. 
2. Kinetic Energy = 0.5 * m * v^2  because velocity is a squared term, doubling the velocity actually quadruples the kinetic energy, making the stopping distance much much greater
3. by the same logic as above, mass is not a squared term, therefore doubling the mass will double the kinetic energy, increasing the stopping distance -- but by not as much as increasing the velocity.
4. because a driver cannot alter the mass of his vehicle, the best way to enter sharp curves would be decreasing velocity (speed)
5. there are many factors that determine the degree of damage (to humans and property in a crash), most notably the size of the vehicle(s) and velocity.