19option (a) is sure...thinking of (c) and (d) !
A shell explodes in a region of negligible gravity field giving out fragments of equal mass, then it's total :
(a) momentum = that before collision
(b) momentum and K.e depend on mass of the fragments
(c) K.E is greater than that before collision
(d) K.E is smaller than that before collision
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11 Answers
19if we are talking of k.e. of the remaining portion of the shell after collision , then k.e. increases !
39Because after explosion the mass fragments gain sudden velocity...?
ok...didn't expect that Aveek :P
1The question is that a shell is exploding into halves , then where does collision take place as stated in the options ? Also thermodynamically speaking , the shell , as a system is doing work to explode , i.e , work done is negative . So in accordance to work- energy theorem , K.E should decrease.
1The shell is not exploding into halves !!!!!!!!!!!!!! The shell can explode into infinite fragments of equal masses !!!!!!!!!
For e.g. if it's mass is 5m, then it can break into m,m,m,m,m mass each :-)
1Yeah,but then also am I wrong ? Because the ans. will remain same for infinite masses.And my question is ------ WHERE IS THE COLLISION HAPPENING ?
1This is not English........it's Physics.....collision means explosion
1well the option d is ony right when the shell already has some k e
if i it is so u cna solve it by finding an analogy between inelastic collision and explsion
39No external forces are acting on the system here. The forces acting are the shell's own(internal). This is why momentum before and after the explosion remains the same, i.e., principle of momentum conservation can be applied.
After explosion, fragments of smaller mass but extremely high velocity are obtained. Thus the increase in kinetic energy.
(K.E proportional to v2, so increase in velocity brings about substantial increase in K.E. where decrease in mass does not decrease K.E. as much)
49suppose shell was at rest....it explodes....
then momentum is always conserved...
and internal energy is converted to kinetic energy....so K.E. increases ... must increase!!