Problem $20$:

The airplane shown in the figure uses a parachute and other means of braking as it slows

down on the runway after landing.

The acceleration of the plane is given by:

$a=-0\mathrm{.}005v^2-4,\frac{m}{s^2}$

Considering the airplane with a velocity $(v)$ of $670k\frac{m}{h}r$ opens its parachute and starts

decelerating at time $t=0,$ use MATLAB to do the following:

a$.$ Solve the system differential equation to obtain an expression for the velocity, $v(t).$

b$.$ Plot the velocity of the airplane versus time $($for $t=0sec$ to $t=7sec)$