| \
Jane running along the level ground with a velocity of 5.6 m/s. She has kinetic energy, but nothing else. \ | \
= | \ \
After: Jane having swung up to some height h, and momentarily at rest. Here she has potential energy, and nothing else. \ | \
\
Initially Jane is running along the ground with a velocty is 4.9 m/sec.
\Kinetic Energy :
.
After that Jane swung up to some height h and come into rest.
\Potential Energy :
.
From the law of conservation of energy,
.

Substitute
and 

Therefore, Jane can swing 1.225 m high.
\\
\
(b)
\From part (a): The Jane swings to a height
.
The height does not depends on the length of the vine or the rope.
\Longer the vine, the smaller will be the angle required for Jane to swing to reach a particular height.
\No, the height does not depends on the length of the vine.