Question

A ball is thrown horizontally from the top of a tower 30m high and lands 15m from its base. What is the ball's initial speed?​

Answer 1

Assuming that there is no initial vertical speed and nothing influences the path of the ball along the way (wind, rain, butterflies or snowmen crossing the street), all you need to do is follow this protocol:

1- calculate how long the ball was in the air

1.1 - you can do this by calculating the time an object takes to drop 30m, by using a number of formulas, of which the simplest would be h=0.5*g*t^2, where h=30, and g=9.81

2- calculate the average horizontal speed of the ball

2.1- you can do this by simply using the formula d=v*t , d=15, and t from the previous answer

2.2- if horizontal velocity is constant, average horizontal velocity equals initial velocity

If done correctly, your result should be around C*2*10^-8 (C = speed of light in vacuum). Or if you are American, 715 barleycorns per second.

Answer 2

15 multiple by 30 answer is 450