# Search results

1. ### Trajectories of motion of bugs

Well, I suppose it isn't too complicated, I mean it has nothing to do with nonlinearity or something. I suspect that the trajectory is a spiral. My problem is to show that this is so. Ok, I went on like this: \frac{d}{dt}\vec{r(t)}=\frac{d}{dt}{r(t)}\vec{e_r}...
2. ### Trajectories of motion of bugs

Hello! I'm thinking about the following problem at the moment: Four bugs sitting at the corners of the unit square begin to chase one another with constant speed, each maintaining the course in the direction of the one pursued. Describe the trajectories of their motions. What is the law of...
3. ### Expression for velocity

Ahhh! Of course - polar coordinates! I've got it now! Thanks guys! :-)
4. ### Expression for velocity

Oh, Jesus sorry...I meant (anglular) impulse of force of course! :)...I've corrected it.
5. ### Expression for velocity

Hey guys! I've got a question. How do we get this expression for the velocity: \dot\vec{r}=\dot{r}+\frac{l^2}{m^2r^2}, where l is the angular impulse of force I thought we could do it like this...
6. ### Point Particle in Magnetic Field

We formulate the law of motion as ODE: m\vec{a}=\frac{q}{c}(\vec{v}\times\vec{B}), where of course \vec{a}=\ddot\vec{r},\vec{v}=\dot\vec{r} So all we have to do is to solve this ODE. But how do we handle the cross-product in an ODE?
7. ### Point Particle in Magnetic Field

Hey, Guys! Could you please give me some guidance for the following problem: A point particle of mass m and charge q moves with an arbitrary initial velocity \vec{v} in constant magnetic field \vec{B}. The point particle is moving under the influence of the...
8. ### Initial Values

Hey, Guys...why silence? Did I ask nonsense? :uhh: I don't think it's nonsense. :grumpy: In the meantime I came across some info on oscillations in Feynman's lectures. It says we cannot specify acceleration with which the motion started because it is determined by the spring, once we...
9. ### Initial Values

Hi, World!! Nice place here! My first post in this forum. :smile: I've got a short question for a start. If we wish to evaluate the constants for the general solution x(t)=C_1e^{-{\lambda_1}t}+C_2e^{-{\lambda_2}t} of this ODE: \ddot{x}+2{\gamma}\dot{x}+{{{\omega}_0}^2}x=0 we can choose the...