Iterative processes can converge to cycles with various periodicities, such as 2-cycles,

His verticak acceleration is 10.02m/s²

Explanation:

Given u = initial velocity = 4.2m/s

H = 2.13m and h =1.25m initial height

At the point where he reaches the crossbar he is no more moving upwards and has reach the maximum height where his final velocity V is 0

So usnng the relation V² = U² + 2a(H - h)

0 = 4.2² + 2a(2.13 - 1.25)

1.76a = 17.64

a = 10.02m/s².

Please note that it is the center of gravity of Brian that is used to measure how high he has jumped.