rotation

[bright musk]

i hve one conceptual doubt

case-1 we hve a rod in a horinzontal plane and a bullet comes and strike it as some point...in these cases we apply momentum conservation the linear one,about the point of collision

case2- we hve a rod which is not hinged and it is rotating with w about com and again one bullet strikes it at some point..Now here when we conserve linear momentum we conserve it about the com unlike in fixed axis rotation..why is this so?

[latent fossil]

<@&1227987967939838003>

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[bright musk]

one reason im able to think of is that in fixed axis rotation..there could be some force of the hinge due to the impulse from bullet so we cannot conserve momentum of whole sys

[leaden nymph]

In case 1, is the rod hinged?

[bright musk]

sorry i forgot to mention

yes it is

[leaden nymph]

Haan, then the hinge exerts some force on the rod

Think of it this way: If the hinge was not there the rod would have some linear momentum right?

But the hinge stop it from moving and "converts" some of this to rotational momentum

[bright musk]

if the rod was initially at rest then some part of kinetic energy of bullet got converted into rotational kE?

and ofc some energy would be lost in collision

[sleek lotus]

Yes correct

[bright musk]

Oky

[bright musk]

+solved @sleek lotus