25.2 Stable and Unstable Equilibrium Points

MIT 8.01 Classical Mechanics, Fall 2016
Instructor: Dr. Peter Dourmashkin

License: Creative Commons BY-NC-SA

[ahmeds]

This instructor is amazing! I wish my school does have someone like him

[hsm]

I so loved graphs, using differentiation to plot maxima/minima points and so on. This video reminded me of that love thanks to a random video on unstable equilibrium.

[jjj-jv]

5:17 unstable equilibrium point
6:21 stable equilibrium point

[matthewa]

How did you get so good at writing backwards?

[tamaghnachaudhuri]

Rather than just giving differential inequalities it's teaches the intuitive way of understanding.... Nice and thank you!!

[VanJake-puus]

Great 👌 your works are so accurate 🤩🤩 thanks so much for your helping

[matthewheck]

I know its filmed through a mirror, but watching him "write backwards" is very distracting

[tougue]

It's just incredible how many of those clever people are left handed...

[rafaelschwertner]

I couldn't understand it very well. Apllying the theorem of stability of equilibria the point x=2 is stable. The analysis of this graph, interpreting the slope, would make sense if the potential function was plotted.

[andyroo]

Peter makes a big mistake at 5:30-6:00. First of all, his description of stable and unstable equilibrium points is not rigorous, but moreso an intuitive explanation of some way of classifying equilibrium points, which is fine. But, the mistake he makes is when describing unstable (and stable) equilibrium points, he says,

"And so if a particle is displaced a little bit from the 0 point, it moves off to the right, and it will continue to feel a force in this direction, and so it will move away from the 0 point of the force" (vice versa for the other side).

Since there is no net force acting on the particle at the equilibrium point, he assumes that the particle starts off a bit past it (in the +x direction), but what he concludes is just false. Feeling a force in the positive x-direction does not mean that the object will actually move in that direction, it just means that there is an instantaneous acceleration in that direction, not necessarily motion in that actual direction. This is one of the most common misconceptions physics learners have when starting off, equating the direction of the force with the direction of the motion, and its a shame he mixes the two. While the overall quality of the course content is high, and I do ignore mistakes of Peter's here and there, like when he treats differentials like fractions or confusingly differentiates between coordinate systems and reference frames when they are the same thing, this is just egregious.

[jonathansum]

Why my professors did not say F =-slop, and she or he told me local max is slowing down? Because of my professors lazy?

[lightlove]

YOU'RE AMAZING!!! Very insightful without becoming overwhelming! 🙏 Thank you so much (for this and the followup video 🤓) This is the last section before our exam in 2 days... and I feel solid on this stuff before even entering the eCovid Classroom today😅👍🙏
✨Watcha me shine, ya'll☀️

[eshnaroy]

This video is so awesome!!! Thank you!!

[vijaymahla]

how you are writing backward please explain i think you have used software

[YourAashique]

Subscribed on 6th Muharram 1445 Hijri, 24th July, 2023 at 8:08 pm (Indian Standard Time).

[ConquerTheCurve]

I have more examples like this on my channel if anyone wants more practice!

[LT-mfuf]

why Fx = -du/dx , why there is a mius sign?

[eduoliveiraAtUTube]

Are these values for a and b arbitrary? If not, how to calculate them? Thanks in advance.