Question

If a is ball thrown vertically upward with an initial velocity of 19.6 m/s, after 5 s what is its final velocity?

Answer 1

just think it logically: if we throw a ball vertically upward, then it should first decelerate until it reaches v=0 and then starts to accelerates from there falling freely. So we can first find how long it takes for the ball to stop: The gravitational acceleration is constant and 9.8 m/s^2, notice that the motion is upward (+y) and the acceleration is down (-y) so it will cause deceleration 9.8 m/s each second, then it will take 2 seconds for the ball to reach its highest point (19.6/9.8=2). Now we can calculate the velocity for 3 seconds (since we found the first 2 second).. Then it will accelerate 9.8 m/s each second so 3*(9.8) = 29.4 is its final velocity

Answer 2

no air resistance is assumed by the way