91Ó°ÊÓ

The speed at which a pipe wrench stuck to the ground,$v=24\mathrm{m}/\mathrm{s}$ .

The initial velocity of a pipe wrench is$v_0=0\mathrm{m}/\mathrm{s}$.

The acceleration due to gravity is, $g=9.8\mathrm{m}/{\mathrm{s}}^2$.

The concept of free fall is used to solve this problem. The velocity when the pipe wrench is about to strike the ground. Assuming this as afree-fall motion, the acceleration of this wrench would be taken as gravitational acceleration.Using these given quantities in the kinematic equation to find the height.

The kinematic equations that can be used to solve this problem are,

$v^2=v_0^2+2as\left(s=H\right)$(i)

$v=v_0+at$(ii)

Assume the downward direction as positive and the upward direction as negative.

Substitute the value in equation (i)

$$\begin{gathered} {24}^2{m}^2/s^2=2×9.8m/s^s×H \\ 576m^2/s^2=19.6m/s^2×H \\ H=29.4\mathrm{m} \end{gathered}$$

So, the height from which the pipe wrench was dropped is$29.4\mathrm{m}$

Substitute the value in equation (ii)

$$\begin{gathered} 24m/s=0+9.8m/s^2·t \\ 24m/s=9.8m/s^2·t \\ t=2.4489 \\ ≈2.45\mathrm{s} \end{gathered}$$

Therefore, the time taken for the pipe wrench to reach the ground is$2.45\mathrm{s}$.

(ii)Graph of velocity vs time

(iii)Graph of acceleration vs time