Question
A neutron moving at a speed 'v' undergoes a head-on elastic collision with a nucleus of mass number 'A' at rest. The ratio of the kinetic energies of the neutron after and before collision is
Answer: Option A
:
A
Mass of neutron (m1)=1unit. Mass of nucleus (m2)=Aunits.
The velocity of the neutron after the collision is
v1=(m1−m2m1+m2)u=(1−A1+A)u
KE of neutron after collision = 12m1v21=12×1×(1−A1+A)2u2
KE of neutron before collision = 12mu2=12×1×u2=12u2.
Their ratio is (1−A1+A)2, which is choice (a)
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:
A
Mass of neutron (m1)=1unit. Mass of nucleus (m2)=Aunits.
The velocity of the neutron after the collision is
v1=(m1−m2m1+m2)u=(1−A1+A)u
KE of neutron after collision = 12m1v21=12×1×(1−A1+A)2u2
KE of neutron before collision = 12mu2=12×1×u2=12u2.
Their ratio is (1−A1+A)2, which is choice (a)
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