To find the velocity at which the ball will strike the ground, we can use the principles of free fall and the equations of motion.
The equation that relates the final velocity (v) of an object in free fall, the initial velocity (u), the acceleration due to gravity (g), and the distance traveled (h) is:
v^2 = u^2 + 2gh
In this case, the ball is dropped from rest (u = 0), and the height it falls from is 20 meters (h = 20 m). The acceleration due to gravity is given as g = 10 m/s².
Plugging these values into the equation, we get:
v^2 = 0^2 + 2 * 10 m/s² * 20 m
Simplifying the equation:
v^2 = 400 m²/s²
Taking the square root of both sides to solve for v:
v = √(400 m²/s²)
v = 20 m/s
Therefore, the ball will strike the ground with a velocity of 20 m/s.