Two students are on a balcony $20\mathrm{.}0$ m above the street. One student throws a ball $($ball $1)$ vertically downward at $12\mathrm{.}0$ m$/$s; at the same instant, the other student throws a ball $($ball $2)$ vertically upward at the same speed. The second ball just misses the balcony on the way down. 

 

 $($a$)$ What is the difference in the two ball's time in the air?  

 $($b$)$ What is the velocity of each ball as it strikes the ground? 

   

 $($c$)$ How far apart are the balls $0\mathrm{.}800$ s after they are thrown?