Also applies to bikes/motorcycles etc.They also have larger brake discs for that reason. Please try to use laws if possible.
Because some vehicle Didn't carry 4x4 wheel drive. In most of cars the front wheels move only. So car stops and main cause is that the momentum of car is towards the front size. When front brakes are applied the force exerted by the car is transferred to the ground due to the concept of inertia. Inertia- The state of no motion or rest is called inertia or tendency of a body to stay at rest or in motion is called as inertia.
When the car / bike stops, there is a tremendous torque applied that tries to rotate it, lifting the rear tires and pushing the front tires down. In most cases, this means that there is a lot more force pushing the front tires into the ground than the rear tires. The force of friction is proportional to the force pushing the two surfaces together, so the amount of friction between the front tires and the road is much greater than the amount of friction between the rear tires and the road. All of the stopping power comes from this friction.
Just think of the car in motion when you try and stop it. The car has a center of gravity and there is a torque from the loaded weight on front wheels about the CG and similarly there is an opposite torque from the loaded weight on the rear wheels. (The lever arm for each goes from the CG to the front point of contact on the road for the front torque and goes from the CG to the back point of contact on the road for the rear torque.) The sum of which is zero, of course. When you try and stop the car, new torques are added. The lever arm here is from the CG to the ground level, but both have the same rotation as each other, rather then opposite. The additional front torque loads the front of the car downward harder to the road, while the similarly rotating new torque around the CG reduces the loading in the rear (lifts it somewhat.) If you want more details, try the following page. I haven't read it, but did a quick search on google using a few terms I tossed at it and this result looks about right.
