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Laws Of Motion

Question
CBSEENPH11020501

It is found that if a neutron suffers an elastic collinear collision with deuterium at rest, fractional loss of its energy is pd; while for its similar collision with carbon nucleus at rest, fractional loss of energy is pc. The values of pd and pc are respectively :

  • (0,1)

  • (.89,.28)

  • (.28,.89)

  • (0,0)

Solution

B.

(.89,.28)

For collision of a neutron with deuterium:

Applying conservation of momentum:

mv + 0 = mv1 + 2mv2 .....(i)
v2 -v1 = v ...... (ii)

Therefore, Collision is elastic, e = 1

From equ (i) and equ (ii) v1 = -v/3

Pd = 12mv2 -12mv1212mv2 = 89 = 0.89

Now, for the collision of neutron with carbon nucleus

Applying conservation of momentum

mv + 0 = mv1 + 12mv2 ....; (iii)

v = v2-v1  ....(iv)

v1 = -1113 vPc = 12mv2 - 12m1113v212mv2 = 48169 0.28