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9 Mar 2009 12:49:52 IST

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Kinetic Energy - Explosion

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Q1) A shell fired from a canon explodes in mid air. As a result:
a. total momentum increases
b. total momentum decreases.
c. momentum & KE remain conserved
d. total KE increases.

Ans given is (d).

Q2) A shell explodes in a region of negligible gravitational field giving out fragments of equal mass, then its :
a. total momentum is equal to that before explosion
b. total momentum & KE depends on mass of fragments.
c. total KE is greater than that before explosion
d. total KE is smaller than that before explosion.

Ans given is (a) & (d).

My doubt here is that in the first case, total KE is increasing (which should be correct) & in the second case it is decreasing. Why?? Is it b'coz of negligible gravitational field?? If it is this reason than please explain how??

Please reply.

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Comments (6)

Ankit

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9 Mar 2009 13:02:59 IST

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1. The linear momentum will be conserved , because explosion occurs from within. However, KE will increase due to (chemical) potential energy of the explosives.

Ankit

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9 Mar 2009 13:12:09 IST

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For second ans should be c.

Kinetic enrgy also depends upon frame of reference , if it is less then it may due to this factor.

XYZ

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9 Mar 2009 13:13:28 IST

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I do not have any doubts regarding the first question.

My doubt lies in the 2nd question. I want to ask why is the kinetic energy decreasing in a region of negligible gravitational field, according to the given answer???

OR Is the answer given in the 2nd question incorrect???

XYZ

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9 Mar 2009 13:15:59 IST

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I want to ask whether the gravitational field has a role to play in the kinetic energy or not???

Bhaskar Tetarbe

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9 Mar 2009 13:33:54 IST

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@Falling Up can you show how K.E depends of frame of reference ?

XYZ

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9 Mar 2009 13:36:54 IST

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Since the velocity of a body depends on the frame of reference, so does the kinetic energy.

Please reply to my question - Does the kinetic energy depend on the gravitational field or not???

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