Solution To conceptualize this problem, imagine the effect
of the acceleration of the helicopter on the cable. The
higher the upward acceleration, the larger is the tension in
the cable. In turn, the larger the tension, the higher is the
speed of pulses on the cable. Thus, we categorize this problem
as a combination of one involving Newton’s laws and
one involving the speed of pulses on a string. To analyze the
problem, we use the time interval for the pulse to travel
from the hiker to the helicopter to find the speed of the
pulses on the cable: