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Two point charges P1and P2 are moving along positive x-axis. Charge and mass of P1 and P2 are (2uc,60ug)and (-5uc,30ug). At particular instant , if the distance of separation is 9mm and the respective speeds are 400ms-1and 1300ms-1 the distance of maximum separation, then should be???

(No other forces, except electrostatic are acting mutually)

23 Answers

11
Subash ·

bhaiyya if u dont like this method can u pls provide another method

33
Abhishek Priyam ·

[1]

13
MAK ·

agreed... [1]

33
Abhishek Priyam ·

whatever but any prob can be solved without it.. and effictively..

13
MAK ·

hmmm... now d statement is correct pirate... [3]

reduced mass is not blind... u r blind at reduced mass... [4]

33
Abhishek Priyam ·

Actually i am totally blank abt Reduced mass :(

33
Abhishek Priyam ·

reduced mass and COM they r diff naa

COM me ankh jada khula rahta hai... reduced mass is blind... B-(

11
Subash ·

but pirate did u find the method that i posted to be correct

1
gudbye targetiit ·

pirate thats what subhash's doing..."reduced mass" solving frm the frame of centre of mass

33
Abhishek Priyam ·

(x+y) will be max separation..

May be above post is bakwaas because its all biomolecules in my mind for mock tomorrow..

If wrong simply ignore :P

33
Abhishek Priyam ·

Let velocity be v1'and v2' wrt COM

and dist frm COM be l1 and l2..

now let at max sep x and y be dist of q1 and q2 frm COM

Now Kq1q2/(l1+l2)+.5m2(v2')2=kq1q1/(l1+x)

Kq1q2/(l1+l2)+.5m1(v1')2=kq1q1/(l1+y)

33
Abhishek Priyam ·

At max separation Velocity of both is 0 wrt COM of system

1
gudbye targetiit ·

if u could obtain the general expression for separation .....(using coulumnbs law)..then use maxima n minima

11
Subash ·

sir its not my own method

i have doubts here

62
Lokesh Verma ·

subash i think what u are doing is correct..

but i dont like reduced mass concept personally...

If you can understnad it "completely" then it is fine.. other wise it is a recipie for suicide!

11
Subash ·

please correct either me or the equation

11
Subash ·

bhaiyya is correct in the eqn relative velocity is zero

and vcm is constant for max separation

62
Lokesh Verma ·

akshay kinetic energy will not necessarily be zero...

It might so turn out but it is not a necessity!

Take an example in normal colission question

First body is moving with velocity of 5 m/s

2nd by 2 m/s

will the kinetic energy ever be zero???

11
Subash ·

i had thought that one should use either use centre of mass
or reduced mass to reduce the system of masses

can both be used together

11
Subash ·

in the previos post v is relative velocity
and take u to be reduced mass

11
Subash ·

it is in the equation of energy conservation that i m getting a doubt

in the solution it is given like

total energy=1/2(m1+m2)vcm^2+1/2uv^2+q1q2/4piE0r

1
Akshay Pamnani ·

At the point of max. seperation KE=0

1
Akshay Pamnani ·

Use energy conservation

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