Disclaimer from Professor Sarma: A lecture is like a live performance – there are no retakes. So when you watch these videos, please keep in mind that I am human, and I make mistakes. For example, at minute 12 of the video of Lec #2 I make a mistake when I describe why the earth is an approximate inertial frame. What I mean to say is that the Earth, though moving, is accelerating relatively slowly with respect to some imaginary but real inertial frame when compared with, say a space-craft. So we treat it as an inertial frame, and experiments show that that is a good approximation. That's not how I say it in the video, but the students did understand what I meant because the staff of the class interact with the students in a number of ways. So watch these videos but stay alert – and keep in mind that besides making mistakes, I also sometimes joke with my students.
The "spider on a Frisbee" problem
Kinematics using first principles: "downconvert" to ground frame