An Alpha particle collides elastically with a stationary nucleus and continues moving at angle of 60 o with respect to the oiginaldirection of motion.The nucleus recoils at an angle of 30 o with respect to this direction. What is the mass number of the nucleus?

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Answers

2016-02-06T01:59:15+05:30
BY law of conservation of momentum
Pintial= P final
let m be mass number of nucleus , v be velocity of alpha particle mass no of alpha=4
now
4*v + m*0 = 4 * v cos60 + m * v cos 30
4v = 4v/2 +√3 m v/2
4 = 2 + √3 m/2
2=√3m/2
m=4/√3
m= 2.3
but m is integer 
m=2

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