Question

Why are seat belts designed in cars to stretch somewhat in a collision?

Answer 1

When a car is moving with a high velocity, its momentum is also high and the people in the vehicle are also in the same momentum. We know that MOMENTUM is INVERSELY PROPORTIONAL TO TIME. So if the momentum is bought to 0 at a short time then force acting on a body is very large. So when a car meets with an accident, the person falling front with the presence of stretchable seat belts as these elastic seat belts reduce the momentum in more time to reduce the force