Summary Class 11 CBSE Physics Chapter 5 : Work Energy Power

Work occurs when force displaces body
P=FxV Power, Force, Velocity Relation Work
in its direction; it's scalar. W=F⇾.S⇾
Rate of doing work is power; P=W or E/t W=F S cos⊝
Power
SI unit=> 1 Watt = 1 J/s; *1 HP = 746 W Work when
F⇾ & S⇾ ⊝=0°=> W=FS (+ve work)
Sum of PE & KE Mechanical/Total Energy
are inclined
Cases ⊝=90°=> W=0 (No/Zero work)
Force is non-conservative if
Non-Conservative F⇾
work depends on path
⊝=180°=> W=-FS (-ve work)

Force is conservative if work Work for const. F⇾ W= F x (S₂-S₁)
depends on initial & final
Conservative
positions, not path. eg.
F⇾ Work for variable F⇾ Fdx
gravitational, spring, magnetic
force etc
Work, Energy
Energy Capacity to do work; 2 types:#Kinetic #Potential
W = -K(Xբ²-Xᵢ²)/2 Body's energy due
and Power
to change in shape Elastic Energy possessed by body due to its motion
PE = -kx²/2 Kinetic
(compressed PE
/stretched) is GPE. Energy Derivation: F⇾ is const.
Conservative PE = 0
KE=mv²/2
F⇾ is variable {Calculus}
Body's energy due to height is
Gravitational PE
GPE. PE = W = F x S = mgh
Work done by force in displacing body
Work is equal to change in KE of body
Energy possessed by body by virtue
Potential Energy
of its position or configuration. F⇾ is const.
Energy Theorem Derivation:
TYPES: #Gravitational #Elastic
KE=(mv²/2) -(mu²/2)
F⇾ is variable {Calculus}