# Find the minimum distance

## Homework Statement

the minimum distance for a car traveling at a speed of 30m/s is 60 m, including the distance traveled during the driver's reaction time of 0.44s. what is the minimum stopping distance for the same car travelling at the speed of 41m/s?

v=30m/s, s=60m
drivers' reaction time = 0.44s

2. The attempt at a solution
because the car traveling at a speed of 30m/s and the distance is 60m, so I find the traveling time 60m/30m/s=2s, and the driver's reaction time is 0.44s, thus the entire stopping time is 2s-0.44s=1.56s.

BvU
Homework Helper
60m / 30 m/s is indeed 2 s. After, say 1.5 seconds, is the speed still 30 m/s ? In other words: can you really use the equation you are using in the case described ? Or do you need some other equations ?

Oh, and: wecome to PF :-)

Jsut so you know: using the template is mandatory. And the template has 1, 2 and 3. Especially 2 is of interest in your situation.

60m / 30 m/s is indeed 2 s. After, say 1.5 seconds, is the speed still 30 m/s ? In other words: can you really use the equation you are using in the case described ? Or do you need some other equations ?

Oh, and: wecome to PF :)

Jsut so you know: using the template is mandatory. And the template has 1, 2 and 3. Especially 2 is of interest in your situation.
the entire travling timie is 2s, I am sure. Then at the end the travel the speed I think is 0 m/s. So I think I can do

0=a*1.56s+30 m/s to fine the a which is -19m/s/s. Because it is the same car, I think the acceleration is the same.
thus, the distance at 41m/s, I think it should be 0.44s*41m/s+ 1/2*(-19m/s/s*(1.56s)2)+41m/s*1.56s

BvU