Answer: 2.04 s
Explanation:
Let the initial velocity be v, Angle of projectile be
Then the horizontal component = v cos θ = 16 m/s
Vertical component of velocity = v sin θ = 20 m/s
Time taken to reach the highest point is half the time taken for total flight.
Time for total flight,


Thus, the football takes 2.04 s to rise to the highest point of its trajectory.
The sphere slow down due to friction force between the surface of the sphere and the surface on that the sphere is rolling . The friction force acting against the motion of the sphere. Thats why it is slowed down. In fact not only a sphere, anything can not slow down untill a force act against it's motion.
It is 20 voltage per hour