2 balls, with masses of M1, M2, are involved in a plastic collision, one dimentional.. the kinetic energy of the ball m1 is 20 times that of m2. at what ratio between the masses will the new mass(m1+m2) move in the direction the lesser energy mass mas moving.(adsbygoogle = window.adsbygoogle || []).push({});

from Ek1=20Ek2

[tex]\frac{m1v1^2}{2}[/tex]=20[tex]\frac{m2v2^2}{2}[/tex]

from this i get, what i'll call ratio(I)

m1/m2=20(v1/v2)^2

i think there are 2 possible scenarios,

*they are both moving in the same direction

*the momentum of M2 is bigger than M1 ==>P2>P1 but Ek1>Ek2, so M1<M2 but V1>V2,

for the 1st scenario there are 2 cases

a)

(M1)-----> (M2)--->

V1>V2 ===} in which case, using the ratio(I) i got before, if v1>v2 thenm1/m2<20

similarily in case 2

(M2)-----> (M1)--->

where v2>v1, here i'll getm1/m2>20

and for the second scenario

(M1)-----> <---(M2)

here i end up withm1/m2<1/20

these answers are similar to the correct answers, according to my textbook, only there ALL the signs are opposites, all the >'s are < etc,

can you see where i have gone wrong or could this be a mistake in the book.

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# Homework Help: Colliding balls with different masses

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