Programming an equation

[gamperz23]

At time t, the velocity v of an object undergoing simple harmonic motion at the end of a spring is given by the formula


v = A * √ k / m * cos ( √ k / m * t )

Here, m is the mass of the object (in g), k is a constant depending on the spring (in g / s2), A is the maximum distance the object moves, and t is the time (in s).
Write a C program which accepts as inputs a time t, mass m, constant k, and distance A, and which computes the velocity of the object according the formula above.
When running your program, use the following inputs:
t: 0.10 s
m: 36.0 g
k: 400 g / s2
A: 5.0 cm

[Banfa]

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Banfa
Administrator

[whodgson]

This appears to be a very simple assignment even though it may take some debugging because of units. Here are the bare bones.
Since k is a spring constant you should declare it as a const.
Likewise for pi.
Since sqrt(k/m) appears twice in the formula assign a variable to it (say z).
Now you can simplify the solution by:

cin>>t>>m>>A; //get the 3 variables, (k already declared).
  v=A*z;
 v*=cos(z*t);//calculate v (rememeber cos (arguement) in radians (deg*pi/180)
cout<<v;

[donbock]

Following up on whodgson's comment that the cos() function in C requires an argument in radians ...

Your formula requires you to compute the cosine of squareRoot(k/m)*t. This cosine argument is dimensionless. Your problem statement provides no clue whether the computed value of this argument is in degrees or radians.

I think it is ok for you to back to your teacher and ask if the actual dimensions for k are g-(deg/sec)^2 or g-(rad/sec)^2.

[whodgson]

Ummm.
In this sort of motion (SHM) angular velocity is sort of synonymous with angular frequency ie w^2=k/m or w=sqrt(k/m)
The units of k are N/m or kg/sec^2 so the units of k/m are kg/s^2/kg=s^-2
When the sqrt of this is taken the unit of frequency is in rad/s.
(recall f=w/2*pi = 1/2*pi * sqrt(k/m)
But you are right in a sense because radian is not really a propper unit.
Quite confusing really.