Tool · Mars physics
Mars vs Earth Braking Distance
On Mars a rally car needs about 125 metres and 9 seconds to stop from 100 km/h on loose ground — 2.4× the 52.5 m the same tires need on Earth gravel. Gravity is 38% of Earth's, so the tires press down with far less force. Change the speed, the planet or the ground below.
The game’s default ground. On Earth, the same tires on the same soil behave like rally gravel.
How it is worked out
Braking is limited by grip: with ABS holding each tire at the peak of its grip, the car slows at the whole grip budget, which has two parts. Friction, µ·g, scales with gravity. Cohesion, c, is the soil's own shear strength — loose regolith holds on to a tire a little — and does not scale with gravity at all.
a = µ·g + c d = v·treact + v² / 2a t = treact + v / a
That second term is why Mars stops 2.4× longer than Earth on the same ground, not the full 2.64× that gravity alone would give: cohesion is a bigger share of a small budget. The ground types are the three in Mars Rally Championship, with the constants its physics uses — tire friction 0.70 on loose regolith, 0.81 on hardpack, 0.53 on cracked polygon ground. Rolling resistance and air drag are left out; on Mars together they add well under 0.2 m/s², and the thin air gives no downforce.
| From | Mars (3.72 m/s²) | Earth (9.81 m/s²) | Moon (1.62 m/s²) |
|---|---|---|---|
| 50 km/h | 31.3 m | 13.1 m | 59.8 m |
| 100 km/h | 125.1 m | 52.5 m | 239 m |
| 150 km/h | 281.5 m | 118.2 m | 537.8 m |
| 200 km/h | 500.4 m | 210 m | 956.1 m |
The long version, with the physics and what it does to a racing line, is in braking distance on Mars vs Earth. To feel it rather than read it, the game's tutorial has a braking lesson that makes you get under 15 km/h before a stop line.