Answer:
35 m/s
Step-by-step explanation:
The time taken for an object with initial velocity of u, a final velocity of v and acceleration a is given by t = (v - u)/a
When the ball reaches maximum height its velocity is 0, so v = 0
Initial Velocity v = 35 m/s
a = -10 m/s²
So time taken to reach maximum height = (0 - 35)/(- 10) = -35/-10 = 3.5 seconds
Once the ball reaches the maximum height it will start falling down with acceleration = + 10 m/s
So final velocity before it hits the ground can be computed from the formula
t = (v - u)/a
Here t = 3.5 seconds, a = 10 m/s and u = 0
So v = u + at = 0 + 10 x 3.5 = 35 m/s
Note: Logically, since the acceleration is constant and same magnitude (but opposite signs), the velocity when the ball hits the ground must be the same as the initial velocity!!
Thus there was no need for any computation in this case!!!!