Question

A runner is jogging in a straight line at a
steady vr= 3.6 km/hr. When the runner is
L= 8.6 km from the finish line, a bird begins
flying straight from the runner to the finish
line at vb= 14.4 km/hr (4 times as fast as
the runner). When the bird reaches the finish
line, it turns around and flies directly back to
the runner.


What cumulative distance does the bird
travel? Even though the bird is a dodo, assume that it occupies only one point in space
(a “zero” length bird), travels in a straight
line, and that it can turn without loss of
speed.

plz help

Answer 1

Explanation:

The runner was 8.6km away from the finish line when the bird starts flying.

Therefore it takes the bird 8.6/14.4 = 0.60 hours for the bird to fly to the finish line.

In that 0.60 hours, the runner would have ran an extra 3.6km/h * 0.6h = 2.16km.

Now, the runner and the bird are flying towards each other. The distance between them is 8.6 - 2.16 = 6.44km and their combined speed is 18.0km.

Hence, they will meet in 6.44/18.0 = 0.36 hours.

Overall, the bird flew for 0.60 + 0.36 = 0.96 hours, and flew 14.4km/h * 0.96h = 13.8km.