average speed and velocity A distance on a straight line from point $a$ to $b$ is $2 km$. A student walks from this line with a speed of 4km/h and another student walks with a speed of 6km/hour. what is the average velocity and average speed of student?
 A: Hint 
Since the path is a straight line so distance=displacement.  
$v_{av}=\dfrac{\text{Total displacement}}{\text{total time interval}}$
A: Hint:  You probably mean "what is the average velocity and average speed of the two students".  If so, when you have two things and are looking for the average, you add them and divide by two.
A: This is an infamous question with multiple legal answers.  Typically one desires to know the average speed with respect to time, but that's not the only possibility.
You can calculate the average speed with respect to distance as well.  That won't help you find out how long a total trip took, for example, but suppose there's an event which is distance-sensitive. Try this: you travel 10 miles at 75 mph and 10 miles at 100 mph, all on a road with a speed limit of 50 mph.  There is a uniform probability of a traffic cop being positioned anywhere along the road.  At what you most likely to be ticketed?   
Now, if I said there was a uniform temporal probability of a cop seeing you, then clearly you'd be more likely to be ticketed at 75 mph because you spend more time at that speed.  
