Problem #17 College Physics - Simple Harmonic Oscillations

Problem #17 College Physics - Simple Harmonic Oscillations

[alishahrudi]

Hello dearest professor,
I just want to tell you, you are like a father to me, even better; and even though you don't really know me, I think I owe you more than my real father.
I am an electrical engineering student (MSc. Telecommunication-fields and waves) and you are the best man I have ever known, I've watched all of your videos on YouTube, especially 8.03 more than once. I really wish that some day I could be at MIT and contribute what you've taught me to others, because that is the goal of my life, that is why I came to being. I really don't know how to say thank you, for everything.

[maisacietto]

I think that the biggest amplitude happens when the elastic force is equal to the maximum static friction between the blocks. If the system was pulled a little farther away, the elastic force would be greater than friction and the blocks would move relative to each other. So, we have x(max)=μmg/k. It’s interesting that x(max) only depends on the mass of the top block, because the table is frictionless.

[AdityaKumar-ijok]

now consider another high school problem, a rod of mass m pivoted from the ceiling is attached to two springs perpendicular to the rod at distance L/2 and L measuring from the ceiling, if the rod is rotated by some small angle, then it will execute SHM, find the time period.

[nazihmansour]

Second-year high school and my goal is to become a great physics professor like you...such an inspiration :)
have a great weekend professor

[nirmalpadwal]

My solution: X(max) = 6(mu)(mg)/k

Thank you for your amazing lectures! Respect from India!

[aarjavjain]

Have you heard about HC VERMA?
Its a really clever book and legend to all jee aspirants in India. The book is called CONCEPTS OF PHYISCS and has the best basic as well as advanced domains covered for each topic. Try it!!!

[oceanz]

awesome video. I love these problems. great way to relax while thinking.

[RekhaKumari-rlfv]

Suppose there is a block of mass m connected to a spring with spring constant k at x=0 on a smooth surface now if we start applying an external force F=(k|x|)/2 then will the resultant motion be simple harmonic motion or not because on both side of mean position there would be a SHM but with different time period????

[adityatripathi]

Just watched ur hamentashen debate. you just nailed it!

[r.s.i]

when masses are not slipping amplitudes of both are same. at the slipping moment, μmg = kx(max). then x(max) = μmg/k.

[andre-vm]

Nice problem as always, Professor. Thank you for sharing!
Just a little question: it doesn't really matter if the springs are at the same or opposite sides, right?

[joud]

Does the mass of the object in the bottom effect my answer? Because I cannot find any relationship between them🙃💔.
In my opinion it effects both the velocity and the acceleration but not the force at a specific location.

[m.l]

I love you man, really don't know how to thank you ❤

[SongSeeker]

One question. When the masses are in the center it seems that one spring is slightly stretched and one comprressed, or are they cut at different lengths? Thx for the problem :)

[abhishektiwari]

Sir, one question:
At a certain factory, 300 kg crates are dropped vertically from
a packing machine onto a conveyor belt moving at 1.20 m/s . (A motor maintains the belt’s constant speed.) The coeffi-
cient of kinetic friction between the belt and each crate is 0.400.
After a short time, slipping between the belt and the crate ceases,
and the crate then moves along with the belt. For the period of
time during which the crate is being brought to rest relative to the
belt, calculate, for a coordinate system at rest in the factory, (a) the
kinetic energy supplied to the crate, (b) the magnitude of the ki-
netic frictional force acting on the crate, and (c) the energy sup-
plied by the motor. (d) Explain why answers (a) and (c) differ.

[esa]

I think I dare ignore harmonic oscillation and deal with the moment when the direction changes. If the springs have no force in the resting position, then the system is symmetric; same displacement causes m to slip at either end of the amplitude. At that moment there are 3 forces acting on m: ma+μmg-kx=0. The whole system has a=2kx/3m. Therefore Xmax=(umg-2kx/2m)/k. Of course if the springs do have force in resting position, then we need to add that to kx, the system is not symmetric and Xmax is smaller.

[Pro.Ruchitadudhatra]

Thank you sir.. Awesome physics.. Awesome you are 🙏

[darksector]

First step: Do force analysis for both objects
Second step: Use work-energy theorem----> -f_k*X_max=-1/2Kx_max^2
Third step: f_k= Mu_k*m*g
Last step: by using algebra you would x_max=(2Mu_k*m*g)/K

[ashaweejoshi]

I got this answer. Xmax=(3Umg)/2K. As per the hint given by you Sir cos(wt)=1 i.e. wt=2π.

[vanmathii]

Sir, when I kept my weighing machine on a bed and I weighed myself it showed only half my weight.so am I accelerating downwards at half of the g