A ramp causes a ball to accelerate at - 4 m/s the ball is rolled up the ramp at 13 m/s find the ball velocity after rolling for 6 seconds you must show your work

a= =- 4 m/s^2 (units!!!)

v = vₒ- a•t ,
0 = vₒ- a•t ,
t = vₒ/a = 13/4 = 3.25 s.
After 3.25 s the velocity of the ball will be zero, and the ball will begin to move downwards.