a small conceptual one

a particle is approaching with a velocity of 5i^+3j^

and it returns after colliding with a velocity of -3i^+4j^

find the coefficient of restitution

37 Answers

11
Subash ·

he meant that the direction of change should be in the normal direction i dont know to derive it mathematically

(and in ur figure just rotate that blue line a bit to make it normal :p)

62
Lokesh Verma ·

hmm... now i got it ...

ok ok got it :)

good work :)

I din realise the first step was that simple :)

gr8 man.. :)

i was trying to calculate the normal reaction in all the dirty way of the world...

33
Abhishek Priyam ·

I was wondering that...
angle of v1 and v2 with N should be equal naaa..

and how v1-v2 gave Normal..

:(
:(

chemistry ate my mind.. :(

33
Abhishek Priyam ·

V1 - V2
|v1| |v2|

should give the normal naa..?

:(
:(

chemistry..

1
Philip Calvert ·

so yes see my post !! they cancel out na......

(in fact he's a genius) evryone know so no need for this

33
Abhishek Priyam ·

yeah.. rohan is a superman..

but i am unable to understand thats it :(

1
Philip Calvert ·

oh sorry i think i misunderstood u

but well first of all its so old even i forgot ...

u talking the diff thing i see sorry for misunderstanding...

lets see again

33
Abhishek Priyam ·

how v1-v2 is normal.. plz expalin....

plz overlook it

1
Philip Calvert ·

damn that blasted power cut

tum bhi soch rahe hoge kya paagal admi hai adhe par hi chhod gaya [1]

ok now see abhishek this is one of the few days you are doing a mistake...

1
Philip Calvert ·

just check ur self again im sure you'll find the mistake

well wat rohan pointed out has to be correct not bcoz he is Rohan(this itself can be taken as a valid reason in many cases[6])
but because from the N L M ...

F = m( v2 - v1 )/t

isn't it so abhi[1] don't u get it even now....

1
Rohan Ghosh ·

ok

direction of normal reaction=-3i^+4j^ - 5i^- 3j^=-8i^ + j^
v1=v initial
v2=vfinal
e=-v2cosβ/v1cosθ
v1.N=-40+3 = > v1cosθ* √65 = -37
v2.N=24+4 = >(-v2vosβ)*√65= 28

dividing we get e=28/37

33
Abhishek Priyam ·

shit...

damn...

this is not my day...

studying chemsitry.. these days.. and it ate my mind up....

[2][2][2][2]

[3]

11
Subash ·

hey philip what is NLM

1
Philip Calvert ·

lol same happened to me abhishek had to put in a few hrs of maths to get myself done with that headache it was causiing [4] lol

Subhash well think a bit [1][1]

11
Subash ·

Newtons Laws Of Motion

is the only thing coming to my sleepy mind right now

33
Abhishek Priyam ·

:P

or else what can it be.. ;)

1
satan92 ·

you see that force exerted by the wall is only along the normal because the component of the velocity of object along the wall doesnt change(as it is frictionless)
further force = dP/dt
=m(v2-v1)/dt
dt is scalar
m is scalar
so F is along v2-v1
but we know F is just the normal

1
skygirl ·

great!

1
skygirl ·

i cudn stop wondering! wat a superb technique!

9
Celestine preetham ·

if we dont assume point of incidence as origin then
there are infinite ans acc to eq that i derived

at any plane if vector makes θ
then vcosθ remains same and vsinθ becoms evsinθ

1
Rohan Ghosh ·

yeah

9
Celestine preetham ·

weres the wall

1
Rohan Ghosh ·

nothing given

9
Celestine preetham ·

is it a smooth wall

9
Celestine preetham ·

3/8
assuming wall at x axis

62
Lokesh Verma ·

celestine.. we cant assume a wall at the x axis!!

i think we are talking about a smooth wall (this was a very good quesiton that you asked!)

62
Lokesh Verma ·

Its rohan's quesiton.. i think he will know the answer better than I do!

62
Lokesh Verma ·

I mean the method or what he really intends to ask.. (but as i see it. it is a frictionless wall with the direction of the wall not known!)

9
Celestine preetham ·

is it colliding against heavy wall

62
Lokesh Verma ·

there is no origin!! i dont see any!

are u talking about origin as the point of reflection?

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