91影视

$\begin{array}{rcl}y& =& 36.6\text{m}\\ y_0& =& 12.2\text{m}\\ t& =& \text{2}\text{s}\end{array}$

The problem deals with the kinematic equations of motion. Kinematics is the studies of how a system of bodies moves without taking into account the forces or potential fields that influence the motion. The equations which are used in the study are known as kinematic equations of motion.

Formula:

The displacement is given by,

$螖y=v_{0}t+\frac{1}{2}a{t}^2$

The final velocity is given by,

$v_f^2=v_0^2+2a螖y$

Assume that the downward direction is positive and the origin is at the ground.

To find the speed use following equation

$y-y_0=v_i脳t+\frac{1}{2}脳a脳t^2$

$36.6-12.2=v_0脳2+\frac{1}{2}脳9.81脳2^2$

$24.4=v_0脳2+19.6$

$v_0=2.4\mathrm{m}/\mathrm{s}$

This is the initial speed with which stone was thrown.

Now using another kinematic equation

$v_f^2=v_0^2+2a螖y$

$v_f^2=2.4^2+2脳9.8脳24.4$

$v_f^2=484$

$v_f=22\text{m/s}$

So, the velocity would be$22\text{m/s}$