a person walks first at a constant speed of 4.90 m/s along a straight line from point a to point b and then back along the line from b to a at a constant speed of 2.90m/s.
(a) what is her average speed over the entire trip? (in m/s)

Her average speed over the entire trip is 3.9 m/s.

Explanation:

We can calculate the average speed as:

s = (s₁ + s₂ ) / n = (4.9 m/s + 2.9 m/s) / 2 = 3.9 m/s

s: average speed over the entire trip

s₁: speed in the first section of the trip(from A to B)

s₂: speed in the second section of the trip (return from B to the final point)

n: number of sections of the trip