Aknight of the round table fires off a vat of burning pitch from his catapult at 15.9 m/s, at 30 ◦ above the horizontal. the acceleration of gravity is 9.8 m/s2 . how long is it in the air?

We can determine the time in the air by the initial vertical velocity component Vyo.To get the Vyo this is the formula;

Vyo = 15.9 sin(30) 
Vyo = 7.95 m/s 

So, the initial vertical velocity component vyo is 7.95 m/s

Vy becomes zero at
 t = Voy/g 
t = 7.95 m/s / 9.8 m/s^2
t = 0.81 s 
It is 0.81 s long that the catapult is in the air.

Iread this book last year so take this with a grain of salt.gene jumps from the tree to compete with finny due to the fact that gene is always trying to do better than finny. he is put under the grasp of peer pressure due to finny almost forcing him to do this. ever since he first jumped finny kept pressuring him to jump since he thought gene enjoyed jumping.rather than uses this answer you should probably just reread chapters 3-4