This Grade 12 IEB Physical Science guide on work, energy, and power covers essential physics concepts, including kinetic and potential energy, the work-energy theorem, and power calculations. It explains energy conservation and efficiency with practical examples, making it perfect for students prep...
The principle of conservation of Em Power Efficiency
X ENER O · definition : In the absence of air resistence or
any external definition :
efficiency is the rat of output power
forces ,
the mechanical
energy (Em) of an object is constant
to input power
En Epi Eki Epf Epf
+
symbols
+
very view devices can transfer form
=
energy from
:
·
in · one
· external forces include :
friction , applied forces and normal forces .
into another without wasting some on the way
k
done on an object :
·
Also note : Emech bottom
=
Emech top ·
using efficiency
calculated : =
power out X 100
· definition The :
product of the displacement otsupp-Ediss Demeen
The theorem
+
power in
work-energy
:
and the component of the force parallel to
a net force
↳ dissapated (lost)
the displacement
·
gives relationship between the work done by
and the change in Kinetic
energy (Emech
·
equation : W =
FAX (J) -
scalar A =
Ep)
States
· :
the work done on an object by a net force is equal
· When work is done , energy Is transfered +
ep
to the change in kinetic energy of the object Ek
ve
and negative work :
Emech
=
· In symbols :
Fret Ax =
DEK
has force
.
· (t) : a in direction of displacement Whet AEK (1)
,
o equation :
=
(Emech-Ek)
energy transfered to object of
law of conservation of
energy
:
B
C) has a force in opposite direction of
:
·
· states : The total energy in a
system cannot be created nor
displacement, energy removed from object
destroyed only transfered from one form to another
S > conservative forces
ie gravitational force
:
does not
(fg)
change mechanical energy of object
&
> f
> Ax
(positive work
Gravitational potential energy (E) non-conservative forces changes the object
< :
mechanical
energy
· definition the :
energy an object possesses due to (negative work)
le
applied forces and tensions
F
its position relative to reference point. DC
Wext Dep + DEK
* >
work done by external forces use
=
· to calculate
equation Ep migh (1)
: =
·
(not on formula sheet) ,
also shown as Next =
EmechA-Emech is
-F
Kinetic energy (EK) which comes from Emecha + Wext =
Emechs
the energy an object possesses dre
so
· definition :
(zero work)
to its motion * > DS
EMV2 + +of
equation (1) x
-
· :
EK =
· definition :
the rate at which work is done
Mechanical
energy (EM) s equation : p = / (W)
·
definition : the sum of
gravitational and kinetic Average power :
energy at a point · the average power required to keep an object at constant speed is
· In Symbols :
Em =
Ep +
EK the product of the applied force (f) and the
average speed (v)
·
at rest EM only made up of Ep only when
is of the object
moving on ground Em made up of Ekonly o equation : P =
Fu (w)
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