→ andrenvq57:謝謝 我了解了 10/14 23:48
※ 引述《andrenvq57 (喂！威，喂？)》之銘言：
: [領域] (題目相關領域)
: 普物
: [來源] (課本習題、考古題、參考書...)
: 沒解答的考古題
: [題目]
: Imagine that we discover a new particle, called Q particle
: by a head-on collision of two photons of energies 500 Mev and 200MeV.
: The photons are annihilated in the process.
: a) what is the mass of the newly discovered particle Q?
: b) what is the kinetic energy of the Q particles produced in this reaction?
: c) what is the momentum of the Q particles?
: d) what si the velocity of the Q particles(magnitude and direction)
: [瓶頸] (寫寫自己的想法，方便大家為你解答)
: a) m = 1.24*10^-27 = 700 MeV/c^2
: b) K = 700 MeV //這我有點不確定..
: c) p = 300 MeV/c
: d) 還在想...
: b的部份讓我很困擾，不是所有的能量都拿來形成Q了嗎
: 不過能量守恆定律 K1 + K2 = Kf = 700 MeV
a)
最後總能量是 500MeV+200MeV=700MeV
而動量是500-200=300MeV
所以靜止質量是
2 2 1/2
(700 -300 ) =200√10 MeV
b)
動能=總能-靜止能量=(700-200√10)MeV
c) 300MeV
d)
v=p/E=(300MeV)/(700MeV)=3/7倍的光速
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