Need some help understanding velocity I have just started learning kinematics and this is just a small question, that I wish for to clarified as it feels a little bit confusing. Below, the difference between speed and velocity is given. I understand that velocity=Change in displacement/time, and so the image of the car on the road confuses me, as if the car turns the corner, shouldn't the number 12.5 be lower along with the change of direction from South to East, speaking of which I feel that it should be SE? Or is the image just an exception? Any help would be much appreciated :)

 A: The textbook example assumes that the car maintains a constant speed as it goes around the corner, and illustrates that velocity (which is a vector quantity) can change even if speed (which is a scalar quantity) does not change.
The car’s average velocity measured over an interval of time before the car turns the corner is $12.5$ m/s due south because its displacement (which is also a vector quantity) is due south. Measured over an interval of time after the car turns the corner, its average velocity is $12.5$ m/s due east because its displacement is due east.
It is true that if you measure the car’s average velocity over an interval that starts when the car is travelling due south and ends when the car is travelling due east, then the direction of this average velocity will be somewhere between south and east, and the magnitude of this average velocity will be less than $12.5$ m/s, but that is not relevant to the example. The example is contrasting the car’s average velocity during intervals whenever it is travelling in a straight line, either before or after the corner.
Notice that I have been talking about average velocity, which is displacement divided by time, because this is simple to visualise and calculate. Eventually you will learn about instantaneous velocity, which is the limit of average velocity as we make the time interval shorter and shorter. As the car goes round the corner the magnitude of its instantaneous velocity is always $12.5$ m/s (because this is its speed, which is constant) and the direction of its instantaneous velocity changes smoothly from due south to due east.
A: Yes, you are right it must be lower while turn as it seems intuitive to you because in everyday life we slow down to take turn.
Now consider a situation you are walking with the velocity of 4 km/h towards south now you have to turn towards east you don't need to slow down and you can continue with same speed but now in different direction(east) so your velocity changes without changing the speed.
So on an average it may possible to mantain same speed after change in direction or while changing the direction in some cases.
