Rotational Mechanics || Advanced Problem || Collision of rod with ground

[@udaychauhan395]

nice problem and nice solution too.

[@tirumalavakati7976]

Sir there will be psuedo torque about B during collision thus there will be a pseudo angular impulse about B

[@tirumalavakati7976]

Why is this wrong??

[@PhysicswithAkashGoyal]

We are not taking the material point of rod... instead we are taking the point on the ground coinciding with the rod... which is an inertial point

[@tsangcahya9162]

sir why we use point b as a point for omega? isn't the velocity of a is respect to center of mass? why if i use the center of mass for point of omega i got the different answer

[@ramakrishnareddy6767]

What is condition if collision is inelastic I mean not perfectly inelastic

[@rajivdixitphysics272]

One more question. If a point mass hits a massive horizontal stick pivoted at its centre in a vertical plane, at a point at some distance from the centre and sticks to it then why do we consider that no torque is acting on the system. And we solve the problem by using COAM . Isn't the point mass applying torque on the rod?

[@chakradhar5884]

Nice question

[@LakshyaMusicals]

Sir in second method in second equation of ang impulse in the termLfinal why you have taken only Iw not mvl/2cos as earlier

[@PhysicswithAkashGoyal]

Angular momentum has two terms one due to Vcm and due to omega... If you write angular momentum about CM then the contribution of the first term is zero as r is zero...

[@LakshyaMusicals]

@@PhysicswithAkashGoyal oh got it sir thank you very much sir for this amazing content 🙏🙂🙂🙏

[@raghuchireddy912]

Akash sir but won't the weight of end A provide a torque about B

[@PhysicswithAkashGoyal]

Weight is non impulsive force and hence any torque due to this will also be non impulsive torque which can't change the angular momentum by a finite amount during infinitesimal time interval of collision

[@raghuchireddy912]

@@PhysicswithAkashGoyal sir is mg always non impulsive

[@PhysicswithAkashGoyal]

Yes in sudden processes like collision constant forces don't contribute much towards impulse. These force need ∆t time for significant impulse. In dt time it's not significant

[@vedbrahmbhattiit-j4497]

sir at 6.00 why we take the defination of e for the bottommost mass only can't we apply for com of the whole rod??

[@chandrashekariyer9329]

No. collision equation is only valid at point of contact and along line of impact

[@srslyumang]

Total P is not conserved due to impulsive forces...

[@doodhnath2]

Sir how can we use equation of e on ball b since rod will also apply impulse and therefore e ki equation as well as energy conservation hold nahi karna chahiye. Sir pls help🙂

[@krishgarg2806]

we can use equation of e irrespective of impulsive forces. It's just velocities of the colliding bodies along the line of impact. energy conservation should technically hold here as e=1.

[@rajivdixitphysics272]

Sir i have a question. Kindly clear my doubt.. While applying COAM about the point B, shouldn't momentum of inertia about B must be considered insted of considering it about c.o.m.?

[@HASANALI-it5mo]

We are taking spin angular momentum and rod is not spining about B

[@shivapandey8958]

That's how angular momentum is defined for body performing CTRM

[@atikshagarwal5147]

Sir why are we not taking any friction? Since normal rkn is impulsive we should have an impulsive kinetic friction

[@PhysicswithAkashGoyal]

There is no velocity along the contact surface at the point of contact when it collides.

[@atikshagarwal5147]

@@PhysicswithAkashGoyal ok sir thank you

[@pankaj.706]

How angular momentum conserve as gravity act. Verticals notion

[@PhysicswithAkashGoyal]

@@pankaj.706 Gravity is non impulsive and torque of non impulsive force is also non impulsive and it cannot change the angular momentum suddenly

[@pankaj.706]

@@PhysicswithAkashGoyal sir this is a new concept not hear that what type of force is non impulsive and impulsive can we take in any questions gravity non impulsive

[@aryansudan2239]

done

[@sodisettyrahulkoushik9719]

Sir isn't the answer vo(1+cos^2theta/sin^2theta)

[@sodisettyrahulkoushik9719]

I got this answer

[@Prashant-fh6px]

🤗🤗

[@anmolempire1197]

I know momentum conservation can't be applied but why so ?? I am not getting satisfactory explanation ( as Due to fact , even if we use it will not give any required result) ?

[@PhysicswithAkashGoyal]

There is impulse applied by ground during collision.

[@anmolempire1197]

@@PhysicswithAkashGoyal okay sir thanks.