Recent content by davidwinth

Also, just in case it was missed, the author presented such a system of equations. 😁

Thank you for the responses. I figured out that I forgot the KE of rotation. I wrote out the equations and was able to solve them numerically. As I suspected, the larger the distance from the rod end, the larger the final velocity of the ball.

Say we have a cylindrical rod of length L and mass M traveling at constant speed S in a direction that is perpendicular to the axis. Further, say that the rod impacts an initially stationary ball of mass m, and the two collide elastically. My question is: does the force experienced by the ball...

Hello, The video is here: It is not strictly a mathematics video. It is an engineering video which uses math so there is no further discussion of this point other than what I noted. I do see that the areas are projections, and I know how dot products work for vectors as far as projecting one...

I am watching a youtube video and the guy is finding the area of triangles in the coordinate planes as shown in the image still below. So the triangle ABC has area a and normal n with direction cosines {L,M,N}. He then says it is obvious from geometry that the area of triangle OAC is given as...

The book is called, "The Machine Design Problem Solver" page 215, and there is no consideration of friction mentioned at all. Of course both the bolt and the members are considered as elastic (hence the reference to their stiffnesses). I have not left out anything that I can see. The entire...

Hello, I am studying through a machine design book and ran across this confusing statement which summarizes the results of an example problem. The problem has a bolt and nut that together hold two members in compression. The stiffness ratio is given as $$K_m = 6K_b$$. The bolt is preloaded with...

Thank you!

The system is shown below. It consists of a rod of length ##L## and mass ##m_b## connecting a disk of radius ##R## and mass ##m_d## to a collar of mass ##m_c## which is in turn free to slide without friction on a vertical and rigid pole. The disk rolls without slipping on the floor. The ends...

Interesting tidbit. Of course, if you had bothered to read any of the above, you'd know that I am clearly not asking, "show me how this works quantitatively without math." You really think a physically intuitive explanation is the very same thing as a quantitative explanation? Wow. They are not...

And I apologize. I didn't realize we were on an elementary school playground, where we pretend that because someone has a particular thing in mind and is not interested in your approach, that he thus "has such a fear" of anything. What a jerk! Please refrain from ever "helping" me again. I was...

Platitudes? You must be having a rough day! If you haven't learned that physics is not merely math, then I definitely can't help you. Yet it is. I'm sorry you think the search for insight beyond number crunching is trite. Nobody else was required to provide calculations when claiming that any...

I am not sure what you mean by, "Eh?" above. See the previous replies where I was told this technique lets you use "any coordinates you like" and similar. Your comment that L*d(phi)/dt will not work for any other angle (other than phi+C) contradicts what others have said. Mysticism is not any...

Thanks everyone. The consensus seems to be that picking any random angle "just works" for any problem, whether there is any physically interpretable reason apparent or not. So, one could use the angle the top surface makes with the ground, either of the other two angles in the triangle I drew...

Thank you for replying! I do agree with you about generalized coordinates and their usefulness. However, I think you missed the point. My question is specifically about how it can be correct to describe the translational velocity of the center of mass by using an angle that is not the angle...