Astudent walks 144 m west, and then turns around and walks 89 m east if this takes place in a 7.5-minute interval, what is the student's average velocity in meters
second? what is the student's average speed?

The average speed is 0.517 m/s

The average velocity is 0.12 m/s west

Explanation:

When dividing the total distance covered by object by time, we get the value for average speed.

Calculate the distance without consideration of motion’s direction. So, the distance walks 144 m first, and then another 89 m, so the total distance covered is

d = 144 + 89 = 233 meters

Given t = 7.5 minutes. Convert minute into seconds,  

So, the average speed can be calculates as below,

When dividing the object’s displacement by time taken, we can calculate average velocity.

In given case, the students walks 144 m west first, and then 89 m east. The displacement is the distance in a straight line between the initial and final position: therefore, in this case, the displacement is

d = 144 (west) - 89 (east) = 55 m (west)

The time taken is t = 450 s

So, the average velocity is

And the direction is west (the same as the displacement).