An 8-mev neutron is inelastically scattered from a barium nucleus. what is the average energy of the emergent inelastic neutrons?

7.45 Mev

Explanation:

in this case we need to considerated the following formula

alpha = E/Eo

where:

alpha = (A - 1)square /(A + 1)square

and A is the mass number of nucleus , for this case the Ba is 56

so we replace the values

alpha = (56 - 1)square /(56+ 1)square

alpha = 55²/57²

E = 8×55×55/57×57

E = 7.45 Mev

8 meters above the spring

f=ma newton

f=100x2.5=250n