Answer:
Part a)

Part b)
t = 12 s
Explanation:
Part a)
Tension in the rope at a distance x from the lower end is given as

so the speed of the wave at that position is given as

here we know that

now we have


Part b)
time taken by the wave to reach the top is given as




Answer:
The period is
Explanation:
From the question we are told that
The mass is 
The extension of the spring is 
The spring constant for this is mathematically represented as

Where F is the force on the spring which is mathematically evaluated as


So


The period of oscillation is mathematically evaluated as
substituting values
For those seeking for the answer, its a source of electrical energy.
50 strands is the standard procedure