Answer 3—The surface gravity of Mars is only about 38% that of Earth. The friction of the tires on the surface is directly proportional to the normal force, so the tires will slip at just 38% of the maximum braking effort available on Earth. The energy of an automobile at a given speed is the same regardless of gravity, and this must be dissipated to stop it. This total work equals decelerating force × distance, where the decelerating force is proportional to the normal force (by the coefficient of friction). Therefore, all other things being equal, stopping distances on Mars will be about 2.6× as long as they are on Earth.

Contributor: David Tweed