Answer:
v = 46.55 m/s
Explanation:
It is given that,
A ball is thrown horizontally from the top of a building 0.10 km high, d = 0.1 km = 100 m
The ball strikes the ground at a point 65 m horizontally away from and below the point of release, h = 65 m
At maximum height, velocity of the ball is 0. So, using the equation of motion as :

Here, a = g


Let
is the horizontal velocity of the ball. It is calculated as :

Let
is the final speed of the ball in y direction. It can be calculated as :



Let v is the speed of the ball just before it strikes the ground. It is given by :


v = 46.55 m/s
So, the speed of the ball just before it strikes the ground is 46.55 m/s. Hence, this is the required solution.