Recent content by yetar

I am having a hard time figuring this out. Suppose we have a 4x4 matrix A, B and rotation matrix D. Matrix A represent position and orinetation of object1, matrix B represent position and orientation of object2. Matrix D is the position and oreintation of object2 relative to object1. B = D*A...

Homework Statement Suppose we have a horizental massless tube. One end of the tube is welded to seomthing that rotates on an angular velocity of w1=(0, 1, 0), on the other end of the tube there is a disk, which rotates with an angular velocity of w2=(0, 0, 2) The system's angular velocity is...

Homework Statement Does the prinicple of moment always depend on the mass density of the rigid body? I have an example in my book with a pully and the principal of moment in there is calculated depending only on the pully's geometry and the pully mass is not considered in the calculation. Is...

What do I need to understand about rotations in 3D? I know there are rotation matrices which are orthogonal matrices. And there is the angular velocity, which I am not sure if it is true, but I think that an angular velocity w and a position r, hold that v = wxr. But this is more related to...

So the inertia tensot J=RMR(T) would change if it is calculated relative to a frame with different axes direction or different origin. Where R would change if the axes direction change, and M would change if the origin change? If the moment of inertia is I = DJD(T) where D is the axes the...

Does this belong to the advanced physics? If so, please move it to the advanced physics. Thank you.

Homework Statement I am trying to understand euler's equations of motion. First of all, relative to what point do we need to calculate the inertia tensor(J)? Do we calculate it relativ to the world origin? or body origin? The torque may be calculated as: T = dL/dt = DL/Dt + wxL = D(Jw)/Dt...

What matrices do you need?

Thank you. Only about the direction of the angular position, if you in a right handed coordinate system, then you use your right hand to check for the direction? and in a left hand coordinate system you use your left hand? Because anti clockwise can be understood in two ways, depending if you...

I am reading a book called "Game physics" by David H Eberly and this is from an exercise in the book. But I didnt copy the exact question here. Is this the wrong place to post this question?

Ok, the purpose of what I read was to find the center of mass of the particle system. This point needs to be the point that when some wedge is holding it, the particle system is in equilibrium. So the sum of the net Force is zero and also the sum of the net torque is zero. From the sum of the...

There is something fundamental I don't understand here, this is the angular position, not the position. So the angular position (0, 0, 1) is not equal to position (0, 0, 1)? Just like the angular velocity (0, 0, 1) means a rotational velocity with speed 1 and rotation axis (0, 0, 1)? So what...

Homework Statement On my book, the torque is defined as: t = rxF F is the a[llied force on a particle, r is the distance of the particle from the origin. However, later on, the book tries to find the center of mass of a 3D particle system and says the torque of a particle is m_i*g*(x_i...

Homework Statement In rigid body, r is the position of a rigid body relative to world coordinates, dr/dt is the rate of change of r in world coordinates. I encountered the term Dr/Dt as the rate of change of r in world coordinates relative to the body coordinates system. And that Dr/Dt =...

Ok, so how do I determine the position of p = (0, 0, 1) by the angulat position? I think the angular position is: (sin(t), -cos(t), t*sqrt(3)) plus or minus a constant. So at t=0 the angular position is (0, -1, 0) and at t=Pi/2. the angular position is (1, 0, Pi*sqrt(3)/2) So the position...