Answer:
Explanation:
Given
length of rope 
velocity while running 
when the person jumps off the bank and hang on the rope then we can treat the person as pendulum with Time period T which is given by




Greatest Possible distance will be covered when person reaches the other extreme end of assumed pendulum (velocity=zero)
therefore he must hang on for 0.5 T time

Explanation:
a. Average speed = distance / time
= 100 m / 70 s
= 1.43 m/s
b. Average displacement = displacement / time
= 0 m / 70 s
= 0 m/s
Distance is the length of the path traveled. Displacement is the difference between the final position and initial position.