A.2.22—Collision energy
- Syllabus
- First assessment 2025
- Objective
- —
- Level
- HL
Track Energy in Collisions and Explosions
Track the energy store
Total energy is conserved, but kinetic energy may be transferred to internal energy, sound, deformation or chemical energy during an interaction.
Collision comparison
Elastic collisions conserve total kinetic energy as well as momentum. Inelastic collisions conserve momentum but have a lower final total kinetic energy.
Explosion comparison
An explosion can convert internal energy into kinetic energy, so final kinetic energy can exceed the initial kinetic energy while total momentum remains conserved.
Common trap
“Kinetic energy is lost” is shorthand for transferred to other stores; it is not destroyed.
A.2.22 Exam Analysis
Assessment in practice
1–3 marksHow it is assessed
The evidence asks learners to show a collision is inelastic or explain why final kinetic energy is lower after a pellet penetrates a ball.
Command terms
Show / Suggest / Explain
What earns marks
To show a collision is inelastic, calculate or compare initial and final total kinetic energy and identify the energy transferred to deformation or other stores. Do not confuse conservation of total energy with conservation of kinetic energy.
Watch for
Saying energy is destroyed rather than identifying work done by contact forces or deformation as the transfer mechanism.
Representative question
Question 1
[Maximum number: 3]
Show that the collision is inelastic.
initial energy 24 mJ and final energy 12 mJ energy is lost/unequal/change in energy is 12 mJ inelastic collisions occur when energy is lost