Question

If you are not wearing a seat belt and the car you are driving hits a fixed barrier, you will hit the steering wheel with some force. This is because of what

Answer 1

This is due to term called "Inertia". Every object, whether stationary or moving, has tendency to stay in its current position or state unless some external forces are applied to it i.e. if a body is moving with some velocity it wiil continue to move untill some external force (like force of friction) is applied on it and a body at rest will not move bt itself (unless external forces like push or pull applied to the stationary body). This tendency to resist changes in their state of motion is described as inertia.

While driving a car with no seat belts buckled, our whole body has same motion but as soon as the car hits a fixed barrier, the lower part of our body which is in contact with the driver's seat stops with the car but the upper portion of our body tries to retain its state of its velocity along the line of motion of the car and so experience a forward jerk and hits the steering wheel

Answer 2

This is because of the pseudo forces. when you are driving the car your velocity is same as that of the car. when the car hits the barrier its velocity becomes zero but your velocity was the same as before. therfore you continue to move forward and you hit the steering