Question

A question about momentum, thank you in advance.
The concept may be easy but perhaps I missed out on something, in attached file, thanks in advance, The answer is A.

Answer 1

Do you know what

a) momentum is?
b) Principle of conservation of momentum is?
c) Elastic and non elastic collisions are?
if yes .. answer briefly then ll help u :)

if no.. better read up on them before u make an attempt to solve this question

Answer 2

Yes I do know all of these (:
Thankssss I do appreciate that

Answer 3

@Mashy

Answer 4

can u tell me briefly each of them? :P

Answer 5

I know that the principle states that
M1u1 + M2+u2 = M1v1 + M2v2

U= velocity before collision and V= velocity after collision

In inelastic collisions the Kinetic energy is not conserved, only momentum is
In Elastic collisions KE AND momentum are both conserved :33
Lmao yeah

Answer 6

ohww. ok.. cool :P

so now..

so lets apply this shall we.

can u tell me what is the total momentum of the two spheres before collision? .. lets take right as positive!

Answer 7

Okay ^-^

Answer 8

2mu + mu = The total momentum before collision (:
Am I right?

Answer 9

nope.. right is positive..

so the sphere one has +2mu
and spehere two (which is coming left ) has -mu..
so whats the total?

Answer 10

Awwwwww !!!

Answer 11

I guess that's the only thing I ALWAYS missed out xD haha
Thank you, the total is , 2mu-mu ::))

Answer 12

so , 2mu-mu = 1mu....?

Answer 13

yes..
correct.. so we know that the final moentum must also be +mu

next.. what is the initial k.e?

the final k.e should also remain the same.. do this check to all the 4 cases..

Answer 14

So the KE is conserved too>? It is an elastic collision then , right?

Answer 15

yea.. thats mentioned in the problem :P

Answer 16

Oh god. Hahahaa xD
YES IT IS.
Lmao

Answer 17

0.5 X 2m X u^2 + 0.5 X m X u^2

Answer 18

ll brb.. try continuing.. dinner time..

and yes.. that is the initial total k.e.. just add them

Answer 19

All right enjoy your meal and TYT (:
I will work on it and I will leave the answer here :)
Thanks a lot.,

Answer 20

enjoy ur dinner ;)

Answer 21

I can't add them properly god,
But 3mu^4.....
Does that make any sense ._. , Lol, I tried :33

Answer 22

And half + half = 1 xD

Answer 23

\[2\frac{m u^2}{2} + \frac{m u^2}{2} = 3 \frac{m u^2}{2}\]

Answer 24

Oh okay so that's how it is

Answer 25

I get what you did up there, but the next step is to find the after the collision values right?(:

Answer 26

the total k.e. after the collision must also remain the same.. right?

so now you can check for each case, what is the momentum and what is the final k.e
the one in which the momentum = initial value, and the k.e. = initial value is the answer

Answer 27

Yes the total KR after the collision will also be 3 mu^2/2

And I get you but I am sorry what do you mean by initial value? As in before the collision?

Answer 28

Ke*

Answer 29

yes.. initial value.. as in the momentum and ke we JUST calculated..

REDO The calculations for all the cases AFTER THE collisions

Answer 30

Awwww Okay I will do so , thanks (:

Answer 31

np , ur wlc :D

Answer 32

:)

Answer 33

Hold up ,.. But I already got the answers for KE and momentum I mean after the collision the momentum is (mu) and the KE is ( 3 mu^2/2 ) so thats after the collision but how do I put them together in order to get answer A..??

Answer 34

@Mashy

Answer 35

you re do the calculation .

like for example in case d

the total momentum = 3m (u/3) = mu .. so momentum is conserved

total k.e = 3m (u^2/9) = mu^2/3.. (which is not as much as before which was 2mu^2/3)
thus k.e is not conserved.. hence d cannot be the option


similarly try with others

Answer 36

Awwwwww now I get it all right no more questions thanks A LOT. :))))))
You meant compare with the options (:
Have a nice day!

Answer 37

yea yea :D..
besides its already 11 30 pm.. so ll have a good night.. good day to you :P

Answer 38

Aww good night it is 9:52 PM where I am haha (:
Sleep tight!

Answer 39

:o its 8:52 here , where are u from @MonsterIsEnergy

Answer 40

@ikram002p I am from Iraq (:
But I do not live there so yeah (:

Answer 41

oh :o
where so u live ?

Answer 42

Dxb