It is observed that the time for the ball to strike the ground (solved) 

Please kindly take a look at this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-FsGBUM5o2-k.html

:)

What is the value for va as you don’t explain it inn the video please reply back ASAP as I need to know for my coursework that is due

No, please see 0:30. We established the datum at the top so that means point B is 1.2 m below the datum.

Va = 20/cos30.5 = 23.2

[-1.2 - (1/2(-9.81)(2.5)^2)]/2.5=11.7825

@@QuestionSolutions 1:31. It's 11.7824 not 11.7825

@@albertdavid It's not 11.7824. See: www.symbolab.com/solver/step-by-step/%5Cfrac%7B%5Cleft%5B-1.2%20-%20%5Cleft(%5Cleft(%5Cfrac%7B1%7D%7B2%7D%5Cright)%5Cleft(-9.81%5Cright)%5Cleft(2.5%5Cright)%5E%7B2%7D%5Cright)%5Cright%5D%7D%7B2.5%7D?or=input or wolfreealpha.gitlab.io/input/?i=%5B-1.2+-+%281%2F2%28-9.81%29%282.5%29%5E2%29%5D%2F2.5

It's 50/2.5 = 20. There isn't a step to show there, we are just simplifying. So if the equation was 4=8xy, then we can write 1=2xy. We divided both sides by 4. Same thing here. Hope that helps!

awesome!