To find average speed, we can use the formula:
speed(m/s) = total distance (m) / time (s)
total distance = 4km + 3km = 7km = 7000m
time = 1.5 hours = 5400s
speed = 7000/5400 = 1.30m/s
To find average velocity, we can use the same formula, but replacing total distance with total displacement.
total displacement = 5km = 5000m (if we use the distance to Sheila's house and the distance from her house to the supermarket as the vector arrows for vector addition, we get 5km, as stated in the question)
velocity = 5000/5400 = 0.926m/s
Because this is a velocity, we need the direction. To find this we can use the formula:
tan (theta) = opposite / adjacent
tan (theta) = 3000/4000
sin(tan (theta))^-1 = sin (3000/4000)^-1
theta = 48.6° East of North or 41.4° North of East
So the average velocity is 0.926m/s [48.6° East of North/ 41.4° North of East]
