Travel time for an accelerating car

[Irukandji]

Hi guys,

i hope i find the right Sub-Forum. Can you please tell me if i calculated it right.

A car speed's up with 5 m/s² to a speed limit of 50Km/h. After it arrived the speedlimit it drives for 30s with the speed of 50km/h. After that it break with a negative acceleration 3.0m/s² to stop the car. How many time it need from start to stop?

My calculation:

(50km/h) : 3,6 = 13,9 m/s

first step:

t = v/a
t= 13,9m/s : 5m/s² = 2,8s

second:

t= 30s

third:

t= v/a =13,9m/s : 3m/s² = 4,6s

Now i add this

t1 + t2 +t3 = 2,8s + 30s + 4,6s = 37,4s

My result is 37,4s. Is this right or iam totaly wrong?

 

[Doc Al]

Looks good to me.

 

[Irukandji]

Thanks this makes me happy.