The units are not consistent - 1 m/s is not the same as 1 km/h.
First thing to do would be to convert from one unit of speed to the other, say km/h to m/s. There are 1000 meters (m) for every kilometer (km) and 3600 seconds (s) for every hour (h), so
So in fact 1 km/h is about 4 times slower than 1 m/s.
Average v = (initial v + final v)/2
= (14 m/s + 0 m/s)/2
= 7 m/s
Your average velocity during braking is 7 m/s
Y = +1-3 = -2
X = -5+7 = +2
D = √2^2-2^2 = 2√1+1 = 2√2 km
Frictional forces act in the direction opposite to the MOTION. That direction could be the same OR opposite to applied force.
-- If you push a loaded heavy wagon from behind, trying to get it going faster, friction is acting against you, opposite to your force.
-- If you push a loaded rolling heavy wagon from in front, trying to make it slow down, friction is acting with you, in the same direction as your force.
-- Opposite to the motion both times.
