Recent content by alterecho

Sorry for the late reply. I just identified an error in my application of the equation. I was taking the square AFTER dividing (r x n) by I in the denominator. I'll have to see how this turns out in my application. Will do some tests. You say |r x n| = 20. Do we need to take the absolute of...

You're right. But when i apply the initial values as: e = 1 V_{i} = (10, -20) W_{i} = 0 r = (0, -20) V_{p} = (10, -20) n = (-1, 1) m = 1 I = 200 For Collision with a Wall/ground, I'm using equation from this site (modified version of the Wikipedia equation)...

You mean V_{f} = V_{i} - \frac{-j}{M} * n ? But we are taking into consideration the normal of the impulse so how is that?

I did use that. Suppose i have, V_{i} = (20, -10), Vp_{i} = (20, -10), ω_{i} = 0, n = (0, 1), M_{a} = 1, I_{a} = 400, r_{a} = (0, -20), I get the V_{f} as (20, -30). This is the procedure i follow, -Calculate the impulse j, -Apply the formula V_{f} = V_{i} - \frac{j}{M} * n (as given in...

Here's an example of the situation I'm working with. The distance vector for point of intersection would be (0, -20) in this case for the ball. I assume the ball as the 1st object and the ground as the second object. I'm also considering the mass of the ground to be infinite and mass of the...

How do i calculate the vector normal?

I'm trying to apply the equation from Wikipedia (http://en.wikipedia.org/wiki/Collision_response) to find the impulse of a collision. How do i find/calculate the surface normal n, which is a unit vector?

Oh. But I've read that for resolution of collision, they take into consideration energy conservation. So how would they resolve it? Are we supposed to know the initial and final velocities and then calculate the final angular velocity from that?

Thanks. I have a further related question. Now suppose i want to extract the final velocity given the initial total energy, the final rotational energy (assuming the potential energies are 0 in this case) using the law of conservation of energy given by, \frac{1}{2}mu^{2} + \frac{1}{2}Iω^{2}...

Its stated that total energy of an isolated system is given by E = \frac{1}{2}mv^{2} + \frac{1}{2}Iω^{2} + mgh. Whats the correct form when the velocity is along 2 axis, that is, along x and y-axis like v = (2, 1)? Should the resultant be taken or just add the kinetic energies along each axis...

That seems to be a good expectation but that image is just rough representation. I'm at loss at how to proceed further. I'll have to think of another way taking all that you said into consideration. Please do let me know if you have a suggestion or a method on how to proceed.

You're right. The thing is, I've been modeling the translational and rotational motion based on assumptions. I really don't know how a rectangular body will react on collision with a wall (in absence of gravity). So how do you think this rectangular body will move after colliding with the wall...

I didn't think of considering m r \times v_i as part of initial angular momentum before. I just tried using this equation, but it does not yield the correct post collision angular velocity w_{f}. Using distance vector r = (1.1, 1.4), m = 1, I = 4.41, v_{i} = (5,0) and v_{f} = (-5, 0), i get a...

So you mean to say that Lw_{i} + Lw_{f} = 0 ? I'm not able to understand/visualize this. Can you please give it in an equation form?

But rotation around center of mass is zero. As i have stated, w_{i} = 0. Do i have to use another equation?