Stopping Distance & Crash Energy
Send two vehicles braking from different speeds and watch how much farther — and how much more violently — the faster one travels before it stops.
Stopping Distance & Crash Energy Simulation
The Physics Behind This Simulation
Both cars decelerate at the same rate, so their motion follows the same SUVAT equation with final velocity v = 0. Solving for displacement gives stopping distance directly from initial speed and deceleration — with speed squared:
Because both stopping distance and kinetic energy depend on u², doubling a vehicle's speed doesn't double the danger — it quadruples both the distance needed to stop and the energy that has to go somewhere in a crash. The Kinetic Energy Calculator and SUVAT Equations Calculator solve these same relationships for any values.
Things to Try
Double the speed
Click "Set Car B = 2× Car A" and brake. Car B travels 4 times farther and carries 4 times the kinetic energy — not twice.
Change the mass
Increase vehicle mass. Stopping distance stays exactly the same (mass cancels out of s = u²/2a), but kinetic energy at the same speed rises — mass matters for crash energy, not for how far you slide.
Switch to ice
Set the road to icy and compare stopping distances to dry asphalt at the same speed — braking deceleration drops by more than 5×, so distance grows by more than 5×.
Match the speeds
Set both cars to the same speed. They stop at exactly the same distance and time, and the ratio readout shows 1.00 — confirming the model treats identical cars identically.