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M1 Mechanics Momentum

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I was wondering how to solve for K.

I was able to do up-to step 2 in the answer sheet, but I am not sure what happened next. What happened to the m and u values? Did they cancel out?

Or are we somehow solving just for K here so we ignore m and u?
(edited 1 year ago)
Original post by Goldenknight
1.jpg

2.PNG

I was wondering how to solve for K.

I was able to do up-to step 2 in the answer sheet, but I am not sure what happened next. What happened to the m and u values? Did they cancel out?

Or are we somehow solving just for K here so we ignore m and u?

mu occurs in each term so divide the equation (each term) by mu.
The question sets up this scenario as each particle is of mass which is a multiple of m, and the speeds are all a multiple of u. Using conservation of momentum, each term therefore have an mu factor which can be divided out.
(edited 1 year ago)
Original post by mqb2766
mu occurs in each term so divide the equation (each term) by mu.
The question sets up this scenario as each particle is of mass which is a multiple of m, and the speeds are all a multiple of u. Using conservation of momentum, each term therefore have an mu factor which can be divided out.


Ahh yes I see it now. Sometimes having lots of variables like this confuses me a bit. Since mostly I do them to solve for an unknown with given other values so its not usually I get something like this. Will keep this in mind tho for next time
(edited 1 year ago)

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