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Grade 12th passMechanics

chapter 9 q. no.59 in second equation there is an external friction force but we apply conservation of momentum how it is possible PLESE HELP

ritesh

10 Years agoGrade 12th pass

13 Answers

Neeti

Approved Tutor Answer10 Years ago

which book? Could you attach a photo of your doubt?

ritesh

10 Years ago

h c verma..........

ritesh

10 Years ago

h c verma..........

ritesh

10 Years ago

h c verma..........

Neeti

10 Years ago

i’m still unable to find it :( could you be a little more specific?

ritesh

10 Years ago

two blocks 1st is 2kg and 2^nd is 4kg separation b/w these 16cm. friction coeff. 0.2.the collision b/w the blocks is perfectly elastic .find separation b/w the two blocks when they come to rest

Neeti

10 Years ago

Yeah it says that the collision is perfectly elastic so we’re supposed to conserve momentum but frictional force is there. have you tried the question by applying conservation of momentum? are you getting the correct answer?

ritesh

10 Years ago

but mam as we study if there is external force(in these q friction) on the system then there is no conservation of momntum.

ritesh

10 Years ago

please explain a little bit to get clear concept of conservation of momntum eq.

Neeti

10 Years ago

Yes Yes i know that. i read a few articles and they state that DURING the collision, (while the collision is happening) , the time interval is very short. the collision happens very quickly so we can assume that $\Delta$ t is very small.

Now we know that F $\Delta$ t = $\Delta$ p.

since $\Delta$ t is very small, the $\Delta$ p transferred to the earth (due to friction) is negligible and can be ignored.

Neeti

10 Years ago

i hope you got it :) feel free to ask any follow-up question :)

ritesh

10 Years ago

thank you very very much. i got dT is very small.......thanku....

Neeti

10 Years ago

You are most welcome :) if you have any other doubt, you can always ask. I’d be more than happy to help :)

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