Rotational Mechanics | Problem Based on Collision | Conservation of Angular Momentum | Sticking Rods

A thin rod is rotating about a pivot on a smooth horizontal surface as shown. Another identical rod is initially kept at rest. Just before the collision pivot is removed. The rods stick to each other and overlapping length is x. find x=x0 for which system has pure translational motion after the collision.
If x=x0/2 then find angular velocity after the collision. Advanced problems Playlist
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[@MEHTATIRTHS-]

Sir do more problems of this kind.It gives me confidence for jee advanced and olympiad

[@grandson_f_phixis9480]

Thank you very much sir Your explanations are always very elaborative. 👏🏽👏👏🏻👏🏾👏🏿👏🏼👏🏽👏

[@akshatgarg3232]

sir I have A doubt at 16:00.... I did not understand how did u write the expression for Li ?...why did u include only I omega term and not mrv? But for the Lf term, you included the mrv term ?

[@Prashant-fh6px]

Awesome😊👏👏 sir 💕 Pls come up with jee main specific topics If possible. It will be great😊👏 🙏

[@PhysicswithAkashGoyal]

will try to do it

[@Prashant-fh6px]

@@PhysicswithAkashGoyal 😁 thnku

[@priyadarshiroy9584]

@@PhysicswithAkashGoyal sir are u in patna right now?

[@PhysicswithAkashGoyal]

yes

[@happysingh6586]

Thank you sir for this prblm

[@modernphysics7474]

Awesome explanation sir 👍👍👍

[@ananyagupta1677]

Sir when we strike a body, say a pen kept on a surface, will it always rotate about its COM?

[@PhysicswithAkashGoyal]

you can assume rotation about any point as distance between any two points of the rod doesn't change. angular velocity of any point wrt any other point on the rod will be same as well. reasons for choosing CM : It has no acceleration in these cases as it depends on external forces only. other points will have accelerations. its velocity will remain constant but velocity of other points will change with time due to acceleration. CM is a special point with so many nice properties attached with it so our choice is CM

[@ananyagupta1677]

@@PhysicswithAkashGoyal thanks for replying so rapidly, sir!! Sir are there any videos on accelerated ICOR cases?

[@krishsharma162]

Also in this question in Method 1 when you write the angular momentum of the red rod with respect to the centre of mass of the two rod I think you should consider the the vcm to be relative velocity of centre of mass of the red Road with respect to the centre of mass of the combined rod system because the centre of mass of the combined system will also have some velocity( =w(l-x/2) just before collision My doubt is : When we write the angular momentum of a system about a fixed point in space then we write M(r×vcm) Plus Icmw in this if we want to write the angular momentum of the system about a point which has some acceleration or some velocity then we should take the relative velocity of centre of mass with respect to that particular point about which we are writing the angular momentum.Isn't it?

[@krishsharma162]

Pls reply this too.

[@PhysicswithAkashGoyal]

Please refer my earlier videos on these topics. you can get them in the playlist collision based problems. kzbin.info/aero/PLb2lQ33Kj0422BWIDkOjS4xmdDL60OVUT We don't choose the material point in writing the equation. we choose a fixed point in space which almost coincides with the CM of the system during the collision. How to solve if we select the material moving point ..... for this you can refer the solution of Q 61 of HCV kzbin.info/www/bejne/m4WYpIWKopV8fNE

[@AT-ly7ud]

Thanks sir 🙏👍🔥🔥

[@sambitbharimalla3069]

Why would the rod keep rotating after the removal of the hinge? Before removal, the hinge was providing a radial force to keep the rod rotating, after removal of the hinge we have no radial force present, so the rod should do a pure translational motion.

[@PhysicswithAkashGoyal]

Just before the collision hinge is removed .... So each point of the rod won't get any significant time to change their velocities. A finite change in velocities in Infinitesimal duration can occur if there is some impulsive force/torque. Since velocities "just before" removal of hinge and" just after" removal of hinge remains same ..... So" effectively" it is rotating about end point.

[@ashokchoudhary4709]

Sir I have some doubts can you please make video on that problems please sir please🙏🙏🙏🙏🙏

[@PhysicswithAkashGoyal]

You can post in the comments with their link.... OR google drive link.... you can also mail me at [e-mail] I will try to solve as and when time permits.

[@realgod4937]

Sir how to revise physics for feb mains sir (im donw with only hcv and pyqs)

[@PhysicswithAkashGoyal]

If you are done with PYQs and HCV honestly and with proper understanding then you have done a very good job .... you can do DC pandey objective book for additional practice

[@mayankazad5121]

Thnk u sir

[@krishsharma162]

Sir if a body is free to rotate then why it always rotate about its centre of mass when external forces applied

[@PhysicswithAkashGoyal]

you can assume rotation about any point as distance between any two points of the rod doesn't change. angular velocity of any point wrt any other point on the rod will be same as well. reasons for choosing CM : It has no acceleration in these cases as it depends on external forces only. other points will have accelerations. its velocity will remain constant but velocity of other points will change with time due to acceleration. CM is a special point with so many nice properties attached with it so our choice is CM

[@krishsharma162]

@@PhysicswithAkashGoyal got it thanks for helping students.