Question

You jog 0.50 kilometers West at 2.0 m/s and after walk West for another 0.50 km at 1.0 m/s.    

a. What is your average speed for the journey?

b. What is your average velocity for whole journey?

Answer 1

Consider the first part of the journey (jogging),
Distance, S1 = 0.5 km = 500 m
Velocity, V1 = 2 m/s
Time taken to travel the first part, t1 = 500 / 2
= 250 s

Consider the second part of the journey (walk)
Distance, S2 = 0.5 km = 500 m.
Velocity, V2 = 1 m/s
Time taken to travel the second part, t2 = 500 / 1
= 500 s

a)
Average speed, Va = (S1 + S2) / (t1 + t2)
= (500 + 500) / (250 + 500)
= 1.3 m/s

b)
Average velocity, Vv = Total displacement / Total time
= (S1 + S2) / (t1 + t2)
= (500 + 500) / (250 + 500)
= 1.3 m/s west