Human reaction time is ~0.25 seconds.
At 20 mph, you’re going ~29 ft per second, so you go ~7.3 ft before you can react.
At 25 mph, that’s ~37 ft per second, so ~9.2 ft before you can react.
The internet says a good car can break at about 15 f/s^2.
At 29 f/s, that comes out to a stopping distance of ~28 ft.
At 37 f/s, that’s ~46 ft.
So Anne, who’s annoying for some reason, needs a total of ~35 ft to stop just before hitting the child.
Norman needs ~9 ft to start decelerating, so by the time he reaches the 35 ft mark (after ~26 ft of hitting the brakes,) it’s been a total of ~0.98 seconds, and he is going ~26 f/s, which is ~18 miles per hour.
Human reaction time is ~0.25 seconds.
At 20 mph, you’re going ~29 ft per second, so you go ~7.3 ft before you can react.
At 25 mph, that’s ~37 ft per second, so ~9.2 ft before you can react.
The internet says a good car can break at about 15 f/s^2.
At 29 f/s, that comes out to a stopping distance of ~28 ft.
At 37 f/s, that’s ~46 ft.
So Anne, who’s annoying for some reason, needs a total of ~35 ft to stop just before hitting the child.
Norman needs ~9 ft to start decelerating, so by the time he reaches the 35 ft mark (after ~26 ft of hitting the brakes,) it’s been a total of ~0.98 seconds, and he is going ~26 f/s, which is ~18 miles per hour.