# Am I doing this right?

6 views (last 30 days)

Show older comments

You are driving a car along a straight road for t = 50s. Assume that friction is negligible but drag is not, where F .5b(v_n-1)^2 , b is a given constant, and v_n-1 is the velocity at the previous time step. For the duration of the trip as described below, calculate the position, velocity, and netacceleration of the car. Use one or more for loops to simulate the behavior of the car starting at t = 0 until t = 50s, with Δ t = 0.5s. Mass of car and you=1428.8kg and b= 1.04 N*s2/m2.

a. Starting from rest, where initial position of x(0) = 0 and v(0) = 0, you apply an initial, constant acceleration of a = 3m/s , until you reach 65 mph(29.05m/s). Upon reaching 65 mph, you maintain a constant velocity.

Here's My code:

m=1428.8;

x=0;

a=3;

for t=[0:.5:50]

v_n=a.*t;

F_drag=.5*(1.04)*v_n;

F=m*a

F_net=F-(F_drag);

if F_net==0

v_n;

p=v_n/a;

end

end

### Answers (2)

Rick Rosson
on 23 Feb 2015

Edited: Rick Rosson
on 23 Feb 2015

% Mass of the vehicle (in kilograms):

m = 1428.8;

% Applied acceleration (in m/s^2):

a_gas = 3;

Time increment (in seconds):

dt = 0.5;

% Time vector (in seconds):

t = (0:dt:50)';

% Number of data samples:

N = length(t);

% Pre-allocate state variables:

x = nan(N,1);

v = nan(N,1);

a = nan(N,1);

% Initial conditions:

x(1) = 0;

v(1) = 0;

a(1) = a_gas;

% Main simulation update loop:

for n = 2:N

...

...

a(n) = ...

v(n) = v(n-1) + ...

x(n) = x(n-1) + ...

...

...

end

##### 6 Comments

Rick Rosson
on 23 Feb 2015

Edited: Rick Rosson
on 23 Feb 2015

I don't understand - you already know how to calculate the drag, you included the calculation in the code that you posted as part of your question.

You have everything you need to solve this problem. Try something in MATLAB, check to see if it works, and if it does not, then try to figure out how to fix it. If you want to learn physics and/or MATLAB, you have to put in some effort. No one is going to do it for you.

Best of luck.

Rick Rosson
on 23 Feb 2015

Image Analyst
on 23 Feb 2015

##### 3 Comments

Image Analyst
on 23 Feb 2015

Rick Rosson
on 23 Feb 2015

Edited: Rick Rosson
on 23 Feb 2015

### See Also

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!