If you see and obstacle on the road while you are driving two processes have to happen for you to totally stop the car:
- Reaction. It takes you a time to hit the brake. That is the reaction time or thinking time. During this while, the car continues moving at the same speed. It is a uniform movement.
- Braking. No matter how well the brakes work, the car will never stop immediately. A time and a distance is required to speed reduce to zero. This second process is a UAM or uniformly accelerated movement whose acceleration is opposite to its velocity.
In this video speeds are expressed in miles per hour (mph). Take into account the fact that 1 mile = 1,609.344 meters.
Considering the information provided in the video:
A) Calculate the reaction time.
B) Calculate the braking time and acceleration.
C) Draw the speed vs time graph for the different initial speeds: 20 mph, 40 mph and 60 mph.