The question deals with two stage motion:
You are driving at 80km/h when you notice a person step out into the road. You need 0.43s to react and start braking. After that, you brake with an acceleration of -4.2m/s². Determine you total stopping distance.
I attempted this question and got a totally unrealistic answer :( Please help !!
- oldschoolLv 74 months agoFavorite Answer
80km/h = 80,000m/3600s = 200/9 m/s
200/9 * 0.43 = 86/9 m before braking.
Vf² - Vo² = 2*a*d = 0² - (200/9)² = 2*(-4.2)*d =
-(200/9)²/(-2*4.2) = d = 58.8m
Total distance = 68m with just 2 s.d.