Physics Force & Motion KU 2024
PMDC Verified Question 8 of 137
A car in motion hits and gets crashed into a tree trunk, what is NOT conserved?
A
Kinetic energy alone
B
Momentum alone
C
Momentum and kinetic energy both
D
Neither kinetic energy nor momentum
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Kinetic energy alone
Concept:

Car crashes are violently inelastic collisions.

Solution:

  • In all macroscopic collisions (including crashes), total linear momentum is strictly conserved across the entire system.


  • However, severe permanent deformation, crunching metal, heat, and loud sounds dissipate massive amounts of kinetic energy.


  • Therefore, Kinetic Energy is the quantity that is decidedly NOT conserved.


Why other options are incorrect:

Momentum is always conserved. Because momentum is conserved, options claiming it isn't are false.

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