Question

Why is work done by external force negative of internal conservative force?

Answer 1

@maheshmeghwal9 anyidea??

Answer 2

no
i haven't studied this chapter
but my advice to search it on google

Answer 3

i did ..nothhing good

Answer 4

becoz it is something like theoretical

Answer 5

think about a spring... you apply force and do work to compress it, what direction is the 'spring force' pointing in that case?

Answer 6

opp

Answer 7

yep

Answer 8

whatater
internal consv.forces?

Answer 9

are*

Answer 10

the spring force, in this case.

Answer 11

and for afreely fallingbody?

Answer 12

in the video of MIT professor walter lewin on electric potential on youtube
there is answer to this question
100% confirm
I have studied that video.

Answer 13

but i can't explain his way.

Answer 14

u have to see that video.

Answer 15

:O

Answer 16

http://www.youtube.com/watch?v=ldJhMDuOGxY

Answer 17

sure, take the electric field: eg. two like charges... one is fixed the other you move...
if you want to push the free one closer to the fixed one, you apply force inward, your work is inward, because the Coulomb force is repulsive...

Answer 18

u must see this also dude
http://www.youtube.com/watch?v=CgqBg44azYk

Answer 19

repulsive = outward

Answer 20

thanks..ill c

Answer 21

professor said
we can take positive sign too
but it depends on something like position of particles or charges.
:D

Answer 22

the main point
u will see in that video is above.

Answer 23

@DLS any problem..

Answer 24

because external and internal forces form action reaction pair, and conservative forces are always balanced. so as to balance, we get the negative :)

Answer 25

thanks everyone!