NEET Physics Nuclei Questions Solved

A neutron with velocity V strikes a stationary deuterium atom, its kinetic energy changes by a factor of 
(a) 1516              (b) 12
(c) 21                (d) None of these

(d) Neutron velocity = v, mass = m
Deuteron contains 1 neutron and 1 proton, mass = 2m

In elastic collision both momentum and K.E. are conserved pi=pf
mv=m1v2+m2v2mv=mv1+2mv2             ... (i)
By conservation of kinetic energy

12mv2=12mv12+12(2m)v22                             ...(ii)

By solving (i) and (ii) we get

v1=m1-m2m1+m2v+2m2(m1+m2)vv1=m1+2m3m=-v3Ki=12mv2, Kf=12mv12Ki-KfKi=1-v12v2=1-19=89           (Fractional change in KE)

Difficulty Level:

  • 34%
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