A person's body is thronw outward as a car rounds a curve on the highway is this newton's 1st 2nd or 3rd law
I don't know which law this is but I know it's AGAINST it. :-).
The situation you described, where a person's body is thrown outward as a car rounds a curve on the highway, is an example of Newton's First Law of Motion.
Newton's First Law, also known as the law of inertia, states that an object at rest will stay at rest, and an object in motion will stay in motion at a constant velocity unless acted upon by an external force. In this case, the person's body tends to resist changes in its state of motion due to its inertia.
As the car rounds the curve, it undergoes an acceleration toward the center of the curve, while the person's body, due to inertia, wants to continue moving in a straight line. This mismatch between the car's acceleration and the person's tendency to continue moving in a straight line results in an outward force on the person.
So, when the person's body is thrown outward, it is an example of Newton's First Law because the person's body tends to continue its straight-line motion (due to inertia) while the car is providing an external force that causes the person to move outward.