An 80.0-kg hiker is trapped on a mountain ledge following a
storm. A helicopter rescues the hiker by hovering above
him and lowering a cable to him. The mass of the cable is
8.00 kg, and its length is 15.0 m. A chair of mass 70.0 kg is
attached to the end of the cable. The hiker attaches himself
to the chair, and the helicopter then accelerates upward.
Terrified by hanging from the cable in midair, the hiker
tries to signal the pilot by sending transverse pulses up the
cable. A pulse takes 0.250 s to travel the length of the cable.
What is the acceleration of the helicopter?เพื่อน