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Questions and Answers
What is the SI unit of energy or work?
What is the definition of work done on an object?
What is mechanical energy composed of?
What is kinetic energy defined as?
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When two identical bodies are in motion, which body has more kinetic energy?
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Study Notes
Energy and Work
- The SI unit of energy and work is the joule (J).
Work Done on an Object
- Work done on an object is defined as the product of the force applied to the object and the distance over which that force is applied, measured in the direction of the force.
- Mathematically, work (W) is expressed as W = F × d × cos(θ), where F is the force, d is the distance, and θ is the angle between the force and the direction of motion.
Mechanical Energy
- Mechanical energy consists of two main components: potential energy and kinetic energy.
- Potential energy is the stored energy based on an object's position or configuration, while kinetic energy is energy associated with motion.
Kinetic Energy
- Kinetic energy is defined as the energy that an object possesses due to its motion, calculated using the formula KE = 0.5 × m × v², where m is mass and v is velocity.
Identical Bodies in Motion
- When two identical bodies are in motion, the body with the higher speed has more kinetic energy, since kinetic energy is directly proportional to the square of the velocity.
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Description
Learn the key highlights of work and energy in Class 9 Science, including the definition of work, SI unit of force, and examples of work done. Understand the relationship between force, displacement, and work.
