You are driving at 100 km/h on a freeway. The car in front brakes suddenly. Why is your stopping distance so much greater than at 50 km/h?

1. Because freeways have a different road surface
2. Because you cannot use your brakes as effectively at high speed
3. Because kinetic energy and stopping distance increase with the square of speed, not linearly
4. Because tyres wear out faster at high speeds