How does KE get changed into internal energy?

AI Thread Summary
Macroscopic kinetic energy (KE) transforms into internal energy when forces act on materials, such as during a collision, where part of the KE is transferred to the impacted object, causing deformation and increasing its internal energy. This transformation occurs as the external force compresses materials at the atomic level, leading to resistance and energy redistribution. In the case of friction, kinetic energy is converted into thermal energy through molecular interactions that randomize the energy, increasing the internal kinetic energy of the molecules. The analogy of a spring illustrates how energy can be stored as potential energy, which is a form of internal energy. Overall, the conversion processes involve interactions at both macroscopic and microscopic levels, leading to changes in internal energy.
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hello

How does macroscopic kinetic energy KE get transformed into internal energy?

Car bumps into trash can and small dent is made in the car.Dent is caused
by force from trash can over certain distance (i.e. car gave part of its KE to trash can and trash can gave part of its KE back to car, which transformed it into internal energy)?

How did this transformation happen?I know if we try to deform a body a net force is created on atomic level that resists external force trying to deform a body even more.
But if I'm not mistaken that act alone doesn't change internal energy?
So what does?

Same question for situation when friction changes KE of a body into internal energy. How exactly do molecules gain speed and thus gain internal kinetic energy?

thank you
 
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On the dent part, think of the analogy where the object being hit has a spring protruding and a ratchet mechanism to hold the spring at any compressed length. As the car hits the spring and compresses it, the spring ratchets in some and then stays at some compressed length. The conversion in energy has been from the car's drop in KE to the spring's increased PE. The increased PE of the spring can be considered internal energy for the thing that the car ran into.
 
hi

And how does friction get transformed into thermal energy?
 
The directed energy of an impact can become randomized at the atomic/molecular level by scattering.
 
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