1......how can a body's potential energy be<->when m and g and h cannot be negative???? also give an example2.......how can body's kinetic energy be< - >???????ExAmpLe Pls[< - > means negative]

the potential energy at a height h above that point is equal to the work which would be required to lift it to that point with uniform velocity . since work is done on the system (i.e a block being lifted) it is conventionally taken as negative.

Kinetic energy is always a relative quantity that can be either negative or positive depending on the direction of kinetic enegy , either in positive x or y direction or negative x or y direction.

Hope that helps

Please approve !

hi...

energy is a scalar quantity...it doesnt have any negative sign...(i may be wrong too)

where did u see energy with direction ????

if i am wrong...plz let me know too.......this question appeals to anybodies' inner core concept of physics...

thanku...

Potential energy can be negative if the body is thrown upwards.Then the gravity will act downward.So it will be negative.

And Kinetic energy can never be negative as it depends upon mass and velocity. mass is always greater than zero. And velocity is greater than or equals to zero.

potential energy is never -ve or +ve , these are  convensions made by us ,

these convensions make various  calculations easy ....

 suppose a ball is placed at the bottom of a  table with  height H then we can say that

potential energy of ball is -mgH wrt surface to table ...

let we take surface of earth as refrence then a particle placed inside H depth will

 have -mgH potential & which is at H height above will have +mgH potential...

h would be negative also.  it  is the vector h whose direction is equally important................  if  from a given reference frame...... if h and g are in opposite direction then one is positive anther is negative.................

approve my answer............

hi,

for example , consider a system of charges(+ve) and a charge(+ve) is brought from infinity near to the system .then negetive work is done on the charge and this work done is stored as electric potential energy.

kinetic energy can never be 0 as m(mass) and v(square)  'the velocity' are always +ve.......

kedar joshi.