2. What is energy?????
●
In physics, energy is one of the basic quantitative
properties describing a physical system or object's
state. Energy can be transformed (converted) among
a number of forms that may each manifest and be
measurable in differing ways. The law of
conservation of energy states that the (total) energy
of a system can increase or decrease only by
transferring it in or out of the system Energy is
measured in SI units of joules (J). Common types of
energy transfer and transformation include processes
such as heating a material, performing mechanical
work on an object, generating or making use of
electric energy, and many chemical reactions.
4. Definition and formula
●
In physics, the kinetic energy of an object is the
energy which it possesses due to its motion.[1] It is
defined as the work needed to accelerate a body of a
given mass from rest to its stated velocity. Having
gained this energy during its acceleration, the body
maintains this kinetic energy unless its speed
changes. The same amount of work is done by the
body in decelerating from its current speed to a state
of rest.
5. Potential energy
●
●
In physics, potential energy is energy stored in a system of
forcefully interacting physical entities .[1] The SI unit for
measuring work and energy is the joule (symbol J).
The term potential energy was introduced by the 19th century
Scottish engineer and physicist William Rankine,[2][3] although
it has links to Greek philosopher Aristotle's concept of
potentiality. Potential energy is associated with forces that act on
a body in a way that depends only on the body's position in
space. These forces can be represented by vector at every point
in space forming what is known as a vector field of forces, or a
force field.
6.
7. Total energy
●
●
The total energy of a system can be calculated by
simple addition when it is composed of multiple
non-interacting parts or has multiple distinct forms
of energy. Common energy forms include the
kinetic energy of a moving object, the radiant
energy carried by light and other electromagnetic
radiation, and various types of potential energy such
as gravitational and elastic.
T.E = P.E.+ K.E = CONSTANT
8. CONSERVATION OF ENERGY
At point 1
TE = PE + KE
= mgh +1/2mv2 ( v2 = 0 )
TE = mgh
At point 2
TE = mg(h-x) + ½ mv2 ( v2 = 2gx )
= mgh – mgx + 12 * 2mgx
= mgh – mgx + mgx
TE = mgh
At point 3
= mgh +1/2mv2 ( h =0) ( v2 = 2gh )
= 1/2m * 2gh
TE = mgh
