THINKING TIME AND CAR CRASH

You are driving a high-end car at 80 kmph. The car glides on the road effortlessly. Suddenly a bull crosses the road, you apply the brake. It is a 'bit late'. You hit the bull. The front of the car is damaged. But, no big damages to the car or the passengers. The bull goes away without a scratch because its weight is more than 1000 kg.

The period between the instant of seeing an event and the instant of car coming to a standstill (stop) is the 'reaction time'. The reaction time has two components. 1. Your thinking time 2. car stopping time. During the two time periods, the car would have traveled some distance. One is named 'thinking distance' and the other is 'breaking distance'.

Thinking distance:
Your thinking time is always the same. But thinking distance changes according to the speed of the car.
Thinking distance = car speed in feet per second* your thinking time in seconds.
On highways, it is frequently recommended that you have two seconds gap between you and the car in front of you. It is because thinking distance is important, giving yourself a couple of seconds of space means you should have plenty of time to figure out the situation and stop at the right time.

Breaking distance:
    When the car runs, it carries energy 1/2mv^2, where m is car's mass and v is its speed.  The energy should be brought to zero on stopping.  The brake gives opposite force and reduce the energy.
Breaking distance= square of the speed in mph/20
Total stopping distance:
    At 20 mph, it takes about 40 feet to stop, 20 feet to react to what is going on in front of you and 20 feet to bring the car to a halt.  At 40 mph, it is 120 feet. At 80 mph, the stopping distance is 400 feet.  That is why, driving at 80 kmph is dangerous and not permitted.  Every extra mile per hour (speed) takes an extra foot of stopping distance.
    Please bear in mind, breaking distance and thinking distance while driving. That will save lot of lives and damages.

FOOT NOTE:

1. We are losing 1.325 million lives worldwide every year due to accidents.
2. Stopping distance further increases on wet road.
3. Moderate speed is the key to safe driving.
4. Human visual reaction time is said to be 180-200 milli seconds.

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