NCERT Solutions for Class 9 Science Chapter 11
Important NCERT Questions
Work and Energy
NCERT Books for Session 2022-2023
CBSE Board and UP Board
Exercises Questions
Page No-158
Questions No-8
Does the transfer of energy take place when you push a huge rock with all your might and fail to move it? Where is the energy you spend going?
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1. Internal Energy Expenditure:
– Muscles in your body contract and work, converting the chemical energy from food into mechanical energy to exert force.
– A significant portion of the energy you spend goes into internal processes, generating heat and internal friction within your body.
2. Overcoming Static Friction:
– The force you apply works against static friction between the rock and the surface it rests upon.
– Energy is expended in attempting to overcome the resistance provided by static friction, but the rock doesn’t move, resulting in energy dissipation as heat.
3. Potential Energy in Deformation:
– Some energy might be absorbed in deforming surfaces (e.g., the rock or ground) slightly.
– This deformation stores potential energy within the material, but it doesn’t cause visible movement of the rock.
4. Sound and Vibrations:
– Interaction between your efforts and the rock’s surface might produce sound or vibrations.
– Energy dissipates as sound waves and vibrations in the surrounding environment.
5. Environmental Factors:
– Some energy disperses due to air resistance, ground absorption, or other environmental factors.
Understanding these points highlights that the energy expended when pushing a rock without moving it gets distributed into internal body processes, overcoming static friction, potential energy from deformation, sound production, vibrations, and environmental factors. The energy spent doesn’t result in significant visible movement of the rock but gets dissipated into various forms and interactions.