coll

In a 1-dimensional collision between two particles, their relative velocity is v1 , before the collision and v2 after the collision.

a) v1=v2 if the collision is elastic.
b) v1= -v2 if the coll is elastic.
c) |v1| = |v2| in all cases.
d) v1= -k v2 in all cases , where k>= 1.
[my question is : how is (c) possible?? Got b and d . but ans is b,c,d. ]

7 Answers

1
Akand ·

if c also possible then shudnt k always be 1???

1
skygirl ·

arey wahi toh mera bhi doubt hai !

1
Akand ·

can u show me d working??.......hw to do it??? i dint understand hw 2 introduce k into it.......

1
skygirl ·

arey it is actually

e = -v2/v1

here k=1/e.

think this way..

106
Asish Mahapatra ·

akand ..
(a) relative vel after coll. = z2-z1 = v2 (here)
rel vel before coll. = c2-c1 = v1 (here)
newtons law of restitution. is (z2-z1)=e(c1-c2)
==> v2=-ev1
if elastic then e=1 so v2=-v1
v1=-v2/e as e≤1 so 1/e ≥1 so it is -kv2 where k≥1

so (b) and (d) (a) can be correct if only mag. is asked but never c...

1
skygirl ·

never C right... ??

i also thot... but jus thot may b i am doind a stupid mistake..

anyways thanx for the confirmation :)

1
Akand ·

ok i took rel vel b4 coll as v1=c1+c2.........i thought they wer movin 2wards each other so it wud add up.......

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