Friction

Step 1: Understanding the role of friction.
Friction is essential for the motion of vehicles on the road. It provides the necessary force for traction between the vehicle's tires and the road surface.
Step 2: Effect of zero friction.
If friction is made zero, the vehicle will not be able to grip the road properly, leading to slipping. The vehicle will not be able to move safely or control its direction.
Step 3: Conclusion.
Without friction, a vehicle cannot move safely on the road as it will lose traction and stability.