An adult dolphin weighs around 1410 n. how fast must he be moving as he leaves the water vertically in order to jump to a height of 1.50 m? ignore air resistance.

D = 1.50 m ( max height )
vf² = vi² + 2 a d
where: vf is the final velocity, vi is the initial velocity and a = - g = - 9.81 m/s²
vf = 0
0² = vi² - 2 · 9.81 · 1.50
vi² = 29.43
vi = √29.43
vi = 5.42 m/s
His velocity as he leaves the water must be 5.42 m/s. 

1. 0.3 •4 is the same as 4 groups of 0.32. 7•0.8 is the same as 7 groups of 0.83. it increases by 0.5 every time, so 0.5x4 it increases by 0.9 every time, so 0.9x5. 0.9•12=10.86. 0.47•5=2.35i can finish the next ones in a separate post