SOLUTION: A runner is jogging in a straight line at a
steady vr= 2.1 km/hr. When the runner is
L= 8.7 km from the finish line, a bird begins
flying straight from the runner to the finish
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-> SOLUTION: A runner is jogging in a straight line at a
steady vr= 2.1 km/hr. When the runner is
L= 8.7 km from the finish line, a bird begins
flying straight from the runner to the finish
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Question 1208244: A runner is jogging in a straight line at a
steady vr= 2.1 km/hr. When the runner is
L= 8.7 km from the finish line, a bird begins
flying straight from the runner to the finish
line at vb= 8.4 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.
Answer in units of km. Answer by Edwin McCravy(20056) (Show Source):
Must be a physics class with such ugly numbers.
The runner and bird begin at A. The finish line is C.
It is 8.7 km from A to C.
x 8.7-x
--------------------------
A B C
The runner is at A and runs x km to B in the same time (t) that the bird flies
from A to C to B. That's 8.7+(8.7-x).
DISTANCE = RATE x TIME
Solve the system
Solve that by substitution, get approximately t=1.66, x=3.48
The bird flies 8.7 + 8.7-x = 17.4-3.48 = 13.92 km.
Edwin
