24when an external force is applied on a system, energy of system is not conserved.....
then we use mechanical energy theorm:
Change of potential energy+Change of Kinetic energy=Work done by non conservative forces
When u lift a box from the floor and put it on an almirah the potential energy of the box increases,but there is no change in its kinetic energy. Is it a violation of the conservation of energy ?
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2 Answers
24
1we apply an additional force on the block against gravity which is just equal and opposite to the weight of the box; so we just do the work against gravity to increase the P.E. of the block
