Basic motion question.Am I correct?

[german1234]

Homework Statement

A car is traveeling at 50km/h.It has to stop over distance of 100m.
Find
(a) constant rate of deceleration neede
(b)time taken to stop

Homework Equations

v^2=u^2+2as
v=u+at

The Attempt at a Solution

(a) 50km/hr= 13.889m/s=u
v=0
s=100m
a= need to find

v^2=u^2+2as

0^2= (13.889)^2 +2a(100)
-192.9=200a
a=-0.9645 m/s^2

(b)
v=u+at
0=13.889-0.9645t
0.9645t=13.889
t=14 seconds

 

[Doc Al]

Looks perfect to me.

 

[german1234]

Thank you so much, Doc Al