Two particles of masses m₁,m₂ with initial speeds u₁,u₂ collide and one becomes internally excited by energy E. If final speeds are v₁,v₂, which energy relation must hold?
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Question

Two particles of masses m₁,m₂ with initial speeds u₁,u₂ collide and one becomes internally excited by energy E. If final speeds are v₁,v₂, which energy relation must hold?

G1 Physics · Accepted Answer

Step 1 — Principle: A short collision conserves linear momentum, whereas kinetic energy may be lost to other forms. Step 2 — Working: Some initial translational kinetic energy E becomes internal excitation energy. Step 3 — Working: Thus Ki=Kf+E, i.e. ½m₁u₁²+½m₂u₂²-E=½m₁v₁²+½m₂v₂². Correct answer: C — ½m₁u₁²+½m₂u₂²-E=½m₁v₁²+½m₂v₂².