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Class 11 Physics | Work Energy Power 01 | Work Done | Constant Force | Basics | Boards ECAT MDCAT
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Class 11 physics students preparing for board exams, ECAT, or MDCAT.
TL;DR
This lecture introduces the physics definition of work, contrasting it with everyday usage. It explains that work requires both a force and displacement in the same direction, and derives the formula W = F·s·cosθ for angled forces. The video also previews upcoming topics like energy, power, and the work-energy theorem.
Key Takeaways
- Physics defines work differently from daily life: work requires both a force applied to an object and displacement of that object in the direction of the force.
- Carrying a heavy load while standing still does zero work in physics because there is no displacement, despite physical effort.
- Work is calculated as the product of force and displacement only when force and displacement are in the same direction.
- When force is applied at an angle to displacement, only the component of force parallel to the displacement does work.
- The component of force perpendicular to displacement does no work; only the parallel component contributes to work done.
- Work done can be expressed as the product of displacement and the component of force in the direction of displacement.
In This Video
- 00:00Introduction to Work Energy Power
Starting the chapter on work, energy, and power with an overview.
- 01:28Daily Life vs Physics Work
Contrasting everyday work with the physics definition of work.
- 02:58Conditions for Work Done
Work requires both force and displacement on an object.
- 05:24Force at an Angle to Displacement
When force is at an angle, only its component along displacement does work.
- 07:56Component of Force in Displacement Direction
Work equals force component along displacement times distance.
- 10:26Rearranging the Work Formula
Work can also be expressed as displacement times force component.
Questions & Answers
What is work in physics?
In physics, work is done when a force is applied to an object and the object undergoes displacement. It is different from work in daily life.
What is the formula for work done?
Work done = Force × Displacement, when force and displacement are in the same direction. If there is an angle, W = F cosθ × s.
When is work done zero?
When a force is applied but there is no displacement, such as standing still while carrying a load on your head, work done is zero.
How to calculate work when there is an angle between force and displacement?
Take the component of force in the direction of displacement: W = F cosθ × s, where θ is the angle between force and displacement.
What will we study in the work, energy, and power chapter?
We will study work, conservative fields, types of energy, the law of conservation of energy, the work-energy theorem, and concepts of power.
What is the definition of work done in physics?
When a force is applied to an object and the object undergoes displacement, it is called work done. It is the product of force and displacement.
Key Terms
- Work Done — In physics, work is done when a force is applied and the object undergoes displacement.
- Component of Force — The part of the force that acts in the direction of displacement does work.
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