| Author |
Message |
![[Post New]](/templates/default/images/icon_minipost_new.gif) 12 Jun 2007 17:14:21 IST
|
|
|
The centrifugal force (or centripetal)of an electron is given by -mv2/r where m is the mass of the electron and v is the velocity and r is the radius............but can anyone please tell me what is the need for the negative sign when the centrifugal(or centripetal)force is given by F=mv2/r
|
God has given you one face, and you
make yourself another.
~William Shakespeare
You were born an original. Don't die a copy.
~John Mason |
|
|
|
12 Jun 2007 17:21:03 IST
|
|
|
Centrifugal force is just a reaction to centripetal force.(Newton's 3 law) So,I feel that is the reason of giving a -sign to centrifugal force centripetal--moving towards the centre centrifugal--coming out from the centre Pls. do rate if u find this useful.
|
Rate me if u like my reply!!!
      
|
this reply: 4 points
(with 0 
in 2 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
12 Jun 2007 17:46:56 IST
|
|
|
Centripetal force is ALONG THE RADIUS TOWARDS THE CENTRE
Centrifugal force is ALONG THE RADIUS AWAY FROM THE CENTRE
just as a quick eg.
if u r in a car going around a curve.......tyres produce neccesary inward Centripetal force (i.e the friction) and u r pushed in OUTWARD direction (-ve sign comes into picture).....this is CENTRIFUGAL force....
Rate If Useful
|
Sometimes One Dream Is Enough To Light Up The Entire October Sky....
First Year Mechanical Engineering
Veermata Jijabai Technological Institute |
this reply: 2 points
(with 0
in 1 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
|
|
|
|
Another point apart from the above two is that
if the force that is
F is negativa then the force acts in inwards direction and acts in outward direction in case F is positive
this can be explained as F=ma
and here a will be negative if it is inward as incase of a pure rolling body the V acts in the outward direction adn thus the A becomes opp of that of V and thus A becomes negative and becomes radially inward (CENTRIPETAL)
&
When the A is radially outward that is in the direction tangential to the V as per rotational Dyanamics than A is radially outward and thus is positive (CENTRIFUGAL)
PLEASE RATE MY EFFORTS IF THEY HAVE CLEARED UR PROblems.
|
Always available for help !
But Remember Don't hesitate to ask a good Question but
Be damn serious for Questioning a weak one.
<TABLE CELLSPACING="1" CELLPADDING="1" BORDER="0">
<TR><TD>
<DIV ALIGN="right">Glitter Graphics</DIV></TD></TR></TABLE>
  
|
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
12 Jun 2007 18:21:09 IST
|
|
|
nikhil
you mean to say centrifugal force is positive and centriprtal force is negative?
|
God has given you one face, and you
make yourself another.
~William Shakespeare
You were born an original. Don't die a copy.
~John Mason |
this reply: 5 points
(with 1
in 1 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
12 Jun 2007 18:32:07 IST
|
|
|
no not at all
I mean to say that
if
you get f as negative then it is centripetal that follows the vector law if you know it . and if positive then it is outward as same as when we say that if a is negative in case of freely falling body then the body is going upwards and if it is positive we say that the motion of the body is downwards in the direction of the gravitational force. understood.
|
Always available for help !
But Remember Don't hesitate to ask a good Question but
Be damn serious for Questioning a weak one.
<TABLE CELLSPACING="1" CELLPADDING="1" BORDER="0">
<TR><TD>
<DIV ALIGN="right">Glitter Graphics</DIV></TD></TR></TABLE>
|
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
12 Jun 2007 18:38:26 IST
|
|
|
no.........i didnt understand...
"F is negative then the force acts in inwards direction and acts in outward direction in case F is positive"
implies centrifugal force is positive and centriprtal force is negative
but how???
and please tell me about this vector law
|
God has given you one face, and you
make yourself another.
~William Shakespeare
You were born an original. Don't die a copy.
~John Mason |
this reply: 5 points
(with 1
in 1 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
12 Jun 2007 19:05:18 IST
|
|
|
see u really need not get the vector law in the picture and confuse ur self .
OK then centripetal force is nothig but any external force like gravitation,tension,,friction etc. The concept of centripetal force is applied to be negative as per ur question above when the magnitude is mv^2/r , but in case of non uniform circular motion the centripetal force is negative in magnitude .
explanation of neg force::::::::::
if speed of a particle in a circle is not constant then the acc has both radial and tangential acceleration .
So when the accn is radially inward that is towards the centre then then it is negative incase of a car moving in circular path and then drifting in the direction opposite to the direction of the centripetal force . I hope that this gave u some idea of the cases of when centripetal is negative and when is it positive.
please rate my efforts.
|
Always available for help !
But Remember Don't hesitate to ask a good Question but
Be damn serious for Questioning a weak one.
<TABLE CELLSPACING="1" CELLPADDING="1" BORDER="0">
<TR><TD>
<DIV ALIGN="right">Glitter Graphics</DIV></TD></TR></TABLE>
|
this reply: 5 points
(with 1
in 1 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
12 Jun 2007 19:12:55 IST
|
|
|
hello srujana are u there I hope u understood it now
|
Always available for help !
But Remember Don't hesitate to ask a good Question but
Be damn serious for Questioning a weak one.
<TABLE CELLSPACING="1" CELLPADDING="1" BORDER="0">
<TR><TD>
<DIV ALIGN="right">Glitter Graphics</DIV></TD></TR></TABLE>
|
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
12 Jun 2007 19:15:36 IST
|
|
|
Thanks for the rating srujana and I more happy that u have understood my concept that i wanted to explain .
Please ask me anyother doubts u have.
|
Always available for help !
But Remember Don't hesitate to ask a good Question but
Be damn serious for Questioning a weak one.
<TABLE CELLSPACING="1" CELLPADDING="1" BORDER="0">
<TR><TD>
<DIV ALIGN="right">Glitter Graphics</DIV></TD></TR></TABLE>
|
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
13 Jun 2007 15:53:37 IST
|
|
|
Hi srujana i feel that there is nothing as negative or positive centrifugal/centripetal force .
Centrifugal force comes into play when the frame of ref is non-inertial.
The sign may b used to show the dirn But if purely depends on u to choose the coordinate axis in prb based on circular motion .So its not imperative to designate centrifugal force as -ve ? Was that given in some book or somewhere...
|
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
13 Jun 2007 16:07:50 IST
|
|
|
s ,it was given in Telugu Akademi book(prescribed for inter 1st year by board of intermediate education,A.P.)
|
God has given you one face, and you
make yourself another.
~William Shakespeare
You were born an original. Don't die a copy.
~John Mason |
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
13 Jun 2007 16:13:00 IST
|
|
|
centrifugal force is a pseudo force. In solving problem with Newton's law the - ve of the centrifugal force is to be added.
|
it is not important where u stand, but in which direction u are moving |
this reply: 0 points
(with 0
in 0 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
14 Jun 2007 16:39:04 IST
|
|
|
Moderation Team
![[Up]](/templates/default/images/icon_up.gif "[Up]"){kind=icon}
