1
Akshay Pamnani
·2009-03-29 03:44:16
iv
some work will also be done against friction
1
sparkle2009
·2009-03-29 03:47:12
The answer given is (iii)
106
Asish Mahapatra
·2009-03-29 03:51:02
then it is wrong.. Stment 2 is definitely correct.
Take a system of two particles of mass m each placed at some distance apart. There is no net force on the system yet after some time they will have increased kinetic energies because work done by the gravitational forces is +ve here... And here they are internal forces in the system... So, internal forces can increase KE.
1
sparkle2009
·2009-03-29 03:56:58
@asish
in the above example,isn't the K.E of the COM is 0 ?
106
Asish Mahapatra
·2009-03-29 04:02:04
how can u calculate KE of a POINT? KE of a body naa?
1
gsns gannavarapu
·2009-03-29 04:06:03
work is done by a force naa......sooo force actin on com mass na.....
106
Asish Mahapatra
·2009-03-29 04:08:22
KE = mv2/2 ... KE of COM is always ZERO bcz COM is a point it has no mass.. mass is assumed to be concentrated there but actually no mass
1
gsns gannavarapu
·2009-03-29 04:26:09
hey but change in KE is onli due 2 wrk done by net external forces actin on d body naa??