Work / कार्य
Work is said to be done when a force acting on a body actually moves it through some distance in the direction related to the force.
जब किसी body पर acting force उसे displacement प्रदान करता है तब Work किया गया माना जाता है।
Work = Fs cos θ
Here F is force, s is displacement and θ is the angle between force and displacement.
यहाँ F = Force, s = Displacement तथा θ = force और displacement के बीच angle है।
SI Unit of Work / कार्य की SI इकाई
The SI unit of work is joule.
Work की SI unit Joule है।
Positive, Negative and Zero Work / धनात्मक ऋणात्मक एवं शून्य कार्य
- If θ > 90°, work is negative.
- If θ < 90°, work is positive.
- If θ = 90°, work is zero.
Coolie Example / कुली का उदाहरण
The source explains that a coolie carrying a load on his head while moving horizontally theoretically does no mechanical work on the load because force and displacement are perpendicular.
जब coolie सिर पर load लेकर horizontal platform पर चलता है तो load पर उसके force और displacement के बीच angle 90° होता है, इसलिए theoretical mechanical work zero होता है।
Energy / ऊर्जा
The capacity of a body to do work is called energy. Energy is a scalar quantity and its unit is joule.
Work करने की capacity को Energy कहते हैं। Energy scalar quantity है तथा इसकी unit Joule है।
Kinetic Energy / गतिज ऊर्जा
Energy possessed by a body due to its motion is called kinetic energy.
Motion के कारण body में possessed energy को Kinetic Energy कहते हैं।
K = 1/2 mv²
Potential Energy / स्थितिज ऊर्जा
Energy developed due to the position or configuration of a body is called potential energy.
Body की position अथवा configuration के कारण stored energy को Potential Energy कहा जाता है।
U = mgh
Law of Conservation of Energy / ऊर्जा संरक्षण का नियम
The source states that the sum of all forms of energy in an isolated system remains constant.
Isolated system में all forms of energy का total sum constant रहता है। इसे Law of Conservation of Energy कहा जाता है।
Power / शक्ति
The rate of doing work is called power.
Work करने की rate को Power कहा जाता है।
Power = Work Done / Time Taken
Important Conversions / महत्वपूर्ण रूपांतरण
- SI unit of Power → Watt
- 1 watt-hour → 3600 joules
- 1 kilowatt-hour → 3.6 × 10⁶ joules
- 1 horsepower → 746 watt
Quick Revision / त्वरित पुनरावृत्ति
- Work unit → Joule
- Energy unit → Joule
- Power unit → Watt
- Kinetic Energy → ½mv²
- Potential Energy → mgh
- Force perpendicular to displacement → Zero work
- 1 HP → 746 W