Recent content by arman.raina

Thank you. All are functions of time. I have not figured out how to write a subscript of 't' on a, to indicate tangential acceleration. so sr/dt=v(r)which is actually v subscript r of t. a⊥=2ω(dr/dt). Does that make sense? It folllows from 2(dr/dt)(dθ/dt)-(r)(d^2θ/dt^2)=0 r is the magnitude of...

Thanks so much. I think I'm almost there. R is indeed a function of time, so the statement is plausible. The a(t) is actually tangential acceleration. In the case of circular motion the statement this is true whenever, since this simplifies to 0=0. I think I need to rephrase the last part of my...

Thanks. I am beginning to get it. F, a and r are all parallel because F=ma. v is only perpendicular to all these in a circular orbit or during certain instances of an ellipse. I am still unsure of why acceleration and radius are parallel mathematically. Under what restrictions is the second...

Link to video http://www.youtube.com/watch?v=6rv9oMXDPMw&feature=youtu.be Sorry about not making sense. I think that is a result of my confusion. In that video from around 3:40 onwards it says that r and a are parallel. I assumed that this is a result of v being perpendicular to both and...

I'm learning vectors. I read somewhere that if a vectors magnitude is constant, then its derivative is perpendicular. However, in polar co-ordinates, I learned something else. The distance of a particle in orbit from a focus is r. if /r/ varies with t even then dr/dt is v and it is...