Question

State law of conservation of energy and prove it in the case of freely falling body​

Answer 1

Answer:

Law of conservation of energy states that:−

Energy can neither be created nor be destroyed.

Energy transforms from one form to another form and, potential energy+ kinetic energy= constant

Proof:−

At point A

K.E=0m/s

P.E=mgh

P.E=mgh

At point B,

K.E.,

2gh=V

2

−O

2

V

2

=2gx

K.E=

2

1

mV

2

K.E=

2

1

m.2gx

K.E=mgx-----------------------------(1)

P.E=mgh

P.E=m.g.(h−x)

P.E=mgh−mgx---------------------(2)

from(1) and (2)

K.E+P.E constant

mgx+mgh−mgx=mgh

mgh=mgh

At point C,

P.E=0

2gh=v

2

−u

2

( initial velocity =0 m/s)

2gh=v

2

K.E=

2

1

.m.v

K.E=

2

1

.m.2gh

K.E=mgh