IIT JEE , AIEEE Forum - Physics , Mechanics

rahuljunior

A hollow sphere is completely filled with water . A hole is made on the equator. the water flows out. DOES THE SPHERE EXECUTE
A)TRANSLATION B)CIRCULAR MOTION C)ROTATION d)S.H.M
i am sorry that i didn't provide thee necessary information. Assume the friction is sufficient enough to execute rotation.

shubham_sachdeva

it is a..it will execute translational motion..

bvsatyaram

When a hole is made on the equator, water escapes from the sphere radially. So, out flow water has radially out momentum. For the net momentum to remain zero, the sphere has to move in the opp direction. Hence the sphere move unidirectionally. Hence translational motion.

edison

There will not be any circular motion as the force is passing through the center of the sphere, thus net torque = 0

Moreover to conserve the momentum there is a translational motion in the sphere.

rooney

But if Sphere is kept on a rough surface, friction would act as well.And thus, rotational motion would occur.

karthik2007

Yeah. The information given is insufficient I think. It could be anything depending on the presence or absence of friction.

ayshwarya

but rooney it is not saidanything about d place on which d sphere kept can u justify urself?

pardesi

it could also be far away from all planets no gravity hence water may not also fall....
well it's more than obvious from the question that other things are assumed ideal

ayshwarya

ok rooney plz answer 2 my quesn which ive made its title is
plz very urgent.

bvsatyaram

Yeah,
Pardesi is right. The answer depends on the environment. Since nothing abt environment is given, it's always suggested to assume that the sphere is in deep space.

rooney

Question is vague. Conditions arent mentioned well. Diff conditions = diff answers.

bvsatyaram

Yeah.. true... but when nothing is given in a problem, we idealise.
That is, we assume every thing is ideal, for "we are ideal students!"

Here the ideal case which we can assume is, deep space. So, the ideal question has an ideal answer!

pardesi

ok i really don't want to sound stupid nor want to continue the arguement any far by all means i think this one is a good question...
any quetsion can have n number of mistakes
for ex if the question reads so-"if a particle is given v=^{[2 ]}

5gl speed at the bootom when attached to a string of length l.Will it reach the top
well answer is yes .but one could equally argue if the breaking stress of the rope isn't sufficient the particle will not reach.But that isn't what the examiner is testing and that's common sense.

similarly here the clear cut aim is to test the idea of a tudent of a sytem with variable mass and that force acting on a body passing through the axis of rotation doesn't provide torque and not to know if friction acn produce torque r not

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