Proton electron neutron and a particles have same momentum. Which of them have highest K.E ?
Correct answer: B. electron
- A. Proton
- B. electron
- C. neutron
- D. a-particle
Explanation
For equal momentum, kinetic energy is K.E. = p²/(2m), so the particle with the smallest mass has the greatest kinetic energy. An electron has much less mass than a proton, neutron, or alpha particle, so it has the highest kinetic energy. The likely wrong choice is a, proton, because students may compare charge or speed instead of using the equal-momentum condition.
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About Kinetic Energy
Kinetic energy is the energy of motion, given for a nonrelativistic object by K = ½mv², so it depends on mass and the square of speed. Questions connect kinetic energy with work through the work energy theorem, calculate changes in kinetic energy, and distinguish it from momentum and potential energy.
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