A stone thrown horizontally from the top of a 10-m tower hits the ground at a point 19 m from the base of the tower. (Ignore any effects due to air resistance.)
(a) Find the speed at which the stone was thrown.
(b) Find the speed of the stone just before it hits the ground.

Question

A stone thrown horizontally from the top of a 10-m tower hits the ground at a point 19 m from the base of the tower. (Ignore any effects due to air resistance.)
(a) Find the speed at which the stone was thrown. 
(b) Find the speed of the stone just before it hits the ground.

anonymous · Answer

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solve the X equation for t
plug it into the Y equation to find Vi
once you have a value Vi, go back to the X equation to find a value for t
then find the final Y velocity using  Final Y velocity = initial Y velocity  -g*t
use the X and Y components of final velocity to find the speed