Why do peoples shoes explode off of their feet if they are hit by a car?

Question

Why do peoples shoes explode off of their feet if they are hit by a car?

Answer 1

G-forces.

Set a shoe loosely on a foot and move that foot from zero miles per hour up to 30 miles per hour in one tenth of a second and the friction that holds the shoe on your foot is overcome by the G-forces subjected to it.

Answer 2

there's no explosion, unless maybe you mean a car propelled by a bomb.

The answer is inertia.  Things at rest tend to stay at rest.  Google it.