Free Fall and Projectiles PHYSICS question?

4) 1 second... you don't have to even know any equations for this. just know the acceleration duw to gravity. It's 9.8 m/s^2 (about 10) so for every second, the projectile is going up is gonna slow down by about 10 m/s. so the object going up at 10 m/s initially will come to a stop (max height) after 1 sec.