how to write a matlab code for this physics problem?

An airplane uses a parachute and other means of braking as it slows down on the runway after landing. Its acceleration is given by a=-0.0035 3v^2-3 m/s^2 . Since , a=dv/dt the rate of change of the velocity is given by: dv/dt=-0.0035v^2-3

Consider an airplane with a velocity of 300 km/h that opens its parachute and starts decelerating at t = 0 s. a. By solving the differential equation, determine and plot the velocity as a function of time from t = 0 s until the airplane stops.

Use numerical integration to determine the distance x the airplane travels as a function of time. Make a plot of x versus time.

[Nick]

Looks a lot like a homework question, show us what you have tried so far.

[sibel yalcin]

syms t
ode='Dv=-0.0035v^-3';
init='v(0)=300';
v=dsolve(ode,init,'t');
y=eval(vectorize(y));
plot(t,y)

For the first part I do not know how to put an interval for t that airplane stops.

Answer 1

[madhan ravi]

Always remember eval is evil: Reason to avoid eval

t=[0 100] %arbitrary time range since we don't know when it reaches ground
x0=300;
opts = odeset('Events',@stopfunc) %it will stop integration when distance becomes zero
[t,x]=ode45(@myod,t,x0,opts)
plot(t,x)
time_when_distance_becomes_zero=t(x==0)

function dvdt = myod(t,x)
 dvdt=-0.0035.*x(1).^2-3;
end
function [position,isterminal,direction] = stopfunc(t,x)
position = x(1); % The value that we want to be zero
isterminal = 1;  % Halt integration 
direction = 0;   % The zero can be approached from either direction
end

 

[sibel yalcin]

Thank you so much, it really helped !

[madhan ravi]

Anytime :) , if my answer helped make sure to accept the answer

Answer 2

[Tarigoppula]

Resolve the horizontal 600lb force in fig a into components acting along the u and vaxes and determine of these components