state the law of conversation of energy
Answers
Mass can neither be created nor be destroyed in chemical change
Law of conservation of energy states that the total mechanical energy which is kinetic energy + potential energy remain constant in an isolated system the energy in a system can neither be created or be destroyed it can simply change its form from one form to another.
According to this principle the total energy remain constant in a system let us make it clear with the example of help of free falling of a ball .
Free falling
let A ball of mass M fall under the effect of gravity alone from a point a at height h above the ground
position a
when ball is at rest here so its velocity is zero then V = 0
K.E = 1/2mv^2
on putting v=0
K.E=0
also,
P.E=Mgh
mechanical energy = potential energy + kinetic energy
M.E. = 0+Mgh
= Mgh
in position B
let ball cover a distance x when it moves from point A to B let V be the velocity of ball at point B
P.E =Mgh
P.E = Mg(h-x)
= mgh-mgx
K.E =1/2mv^2
from third eqn of motion
2as = v^2 -u^2
2gx = v^2. ( as a=g and distance =X )
so.
,
K.E = 1/2m v^2
= 1/2m2gx. (on putting value)
M.E = P.E+K.E
=mgh-mgx + 1/2.2mgx
= mgh. ( after simplification )
Position C
let the ball cover Total distance at when it moves from point A to see let V be the velocity before it touches the ground at point c
P.E. = mgh
(h=0)
P.E = 0
K.E =1/2mv2
v2 - u2 =2gs
v2=2gs
on putting value
K.E = 1/2. 2mgh
= mgh. ( after simplification)
hope this will help you
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