PPT: How Things Work | Science & Pedagogy Paper 2 for CTET & TET Exams - CTET & State TET PDF Download

 Page 1


Work, Power and 
Energy
Page 2


Work, Power and 
Energy
Understanding Work in Physics
Definition
Work occurs when a force 
causes object 
displacement. Work = 
Force × Displacement in 
the direction of force.
Mathematical 
Expression
W = Fd = F cos »d, where 
» is the angle between 
force and displacement. SI 
unit: Joule (J).
Nature of Work
Work is positive (force and 
displacement align), 
negative (force opposes 
displacement), or zero 
(force perpendicular to 
displacement).
Page 3


Work, Power and 
Energy
Understanding Work in Physics
Definition
Work occurs when a force 
causes object 
displacement. Work = 
Force × Displacement in 
the direction of force.
Mathematical 
Expression
W = Fd = F cos »d, where 
» is the angle between 
force and displacement. SI 
unit: Joule (J).
Nature of Work
Work is positive (force and 
displacement align), 
negative (force opposes 
displacement), or zero 
(force perpendicular to 
displacement).
Power: Rate of Doing 
Work
W/t
Basic Formula
Rate of work done
F·v
Alternative Form
Force × velocity
746W
1 Horsepower
Equals 746 watts
Power is the rate at which work is performed. Calculated as 
P = W/t = F·v = Fvcos », where force multiplied by velocity 
gives power. The SI unit is Watt (J/s), with horsepower 
(746W) as another common measure.
Page 4


Work, Power and 
Energy
Understanding Work in Physics
Definition
Work occurs when a force 
causes object 
displacement. Work = 
Force × Displacement in 
the direction of force.
Mathematical 
Expression
W = Fd = F cos »d, where 
» is the angle between 
force and displacement. SI 
unit: Joule (J).
Nature of Work
Work is positive (force and 
displacement align), 
negative (force opposes 
displacement), or zero 
(force perpendicular to 
displacement).
Power: Rate of Doing 
Work
W/t
Basic Formula
Rate of work done
F·v
Alternative Form
Force × velocity
746W
1 Horsepower
Equals 746 watts
Power is the rate at which work is performed. Calculated as 
P = W/t = F·v = Fvcos », where force multiplied by velocity 
gives power. The SI unit is Watt (J/s), with horsepower 
(746W) as another common measure.
Energy: The Capacity to Do Work
Mechanical Energy
Energy from motion 
(kinetic) or position 
(potential). KE = ½mv² or 
p²/2m, while PE = mgh.
Heat Energy
Energy from molecular 
motion. Transfers from hot 
to cold bodies. Measured 
in calories (CGS units).
Conservation of 
Energy
Energy cannot be created 
or destroyed, only 
transformed between 
forms. T otal energy in a 
system remains constant.
Energy is the capacity to do work. It exists as mechanical, heat, light, sound, electrical, chemical, 
solar, and nuclear forms. These forms transform into one another according to the conservation 
law.
Page 5


Work, Power and 
Energy
Understanding Work in Physics
Definition
Work occurs when a force 
causes object 
displacement. Work = 
Force × Displacement in 
the direction of force.
Mathematical 
Expression
W = Fd = F cos »d, where 
» is the angle between 
force and displacement. SI 
unit: Joule (J).
Nature of Work
Work is positive (force and 
displacement align), 
negative (force opposes 
displacement), or zero 
(force perpendicular to 
displacement).
Power: Rate of Doing 
Work
W/t
Basic Formula
Rate of work done
F·v
Alternative Form
Force × velocity
746W
1 Horsepower
Equals 746 watts
Power is the rate at which work is performed. Calculated as 
P = W/t = F·v = Fvcos », where force multiplied by velocity 
gives power. The SI unit is Watt (J/s), with horsepower 
(746W) as another common measure.
Energy: The Capacity to Do Work
Mechanical Energy
Energy from motion 
(kinetic) or position 
(potential). KE = ½mv² or 
p²/2m, while PE = mgh.
Heat Energy
Energy from molecular 
motion. Transfers from hot 
to cold bodies. Measured 
in calories (CGS units).
Conservation of 
Energy
Energy cannot be created 
or destroyed, only 
transformed between 
forms. T otal energy in a 
system remains constant.
Energy is the capacity to do work. It exists as mechanical, heat, light, sound, electrical, chemical, 
solar, and nuclear forms. These forms transform into one another according to the conservation 
law.
Temperature: Measuring Heat Intensity
Definition
T emperature measures heat 
intensity in substances, 
detected by thermometers 
or touch.
Various scales use different 
reference points for water's 
freezing and boiling states.
Temperature Scales
Celsius: 0°C (ice) to 
100°C (steam)
Kelvin: 273K (ice) to 
373K (steam)
Fahrenheit: 32°F (ice) to 
212°F (steam)
Reaumer: 0°R (ice) to 
80°R (steam)
Thermometers
T emperature measuring 
devices:
Clinical: 35°C to 42°C 
range
Laboratory: 10°C to 
110°C range