Answer:
Final speed of the ball, v = 20 m/s.
Step-by-step explanation:
It is given that,
Initial speed of the ball, u = 40 m/s
Time. t = 2 s
We need to find the speed of the ball after 2 seconds. Let it is denoted by v. It can be calculated using first equation of motion as :

Here, a = -g, as the ball is ball is moving under the action of gravity.


v = 20 m/s
So, the speed of the ball after 2 seconds is 20 m/s. Hence, this is the required solution.