Potential energy (MeV)
a. 3 fm.
b. 4 fm.
1 2 3
FIGURE 7.24 Potential energy for two deuterons (Passage
Problems 70-73)
(MeV), a unit commonly used in nuclear physics, and the separation is
10-¹5 m).
c. -3 MeV.
d. 0.3 MeV.
5
in femtometers (1 fm
劉
70 The force between the deuterons is zero at approximately
10
Separation (fm)
c. 3.3 MeV.
d. 3.6 MeV.
=
c. 5 fm.
d. the force is never zero.
71. In order for initially two widely separated deuterons to get close
enough to fuse, their kinetic energy must be about
a. 0.1 MeV.
b. 3 MeV.
72. The energy available in fusion is the energy difference between
that of widely separated deuterons and the bound deutrons after
they've "fallen" into the deep potential well shown in the figure.
That energy is about
a. 0.3 MeV.
b. 1 MeV.
73 When two deuterons are 4 fm apart, the force acting on them
a. is repulsive.
b. is attractive.
c. is zero.
d. can't be determined from the graph.