Aperson 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)

The person's average speed over the entire trip was 3.9 m/s.

Explanation:

The average speed over the trip was:

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

s: speed of the entire trip

s₁: speed in 1° section of the trip

s₂: speed in 2° section of the trip

n: number of sections

The important thing is the speed of the person walking but not the distance travelled during the trip.

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide