a boy standing n a high cliff dives into the ocean below and strikes the water after 2.5 s. what is the boy's velocity when he hits the water? deltav=gxt

Answer 1

As you have already stated,
deltav=gxt

That means the change in velocity (delta V) equals the acceleration of gravity (g = 9.8 m/s^2) times the time spent falling (2.5 s)