#importing modules
import math
from __future__ import division
#Variable declaration
A1=165; #mass number
A2=4; #mass number
R1=7.731; #radius(fermi)
#Calculation
R2=R1*(A2/A1)**(1/3); #radius of He(fermi)
#Result
print "radius of He is",round(R2,4),"fermi"
#importing modules
import math
from __future__ import division
#Variable declaration
n=1.008665; #mass of neutron(amu)
p=1.007276; #mass of proton(amu)
alpha=4.00150; #mass of alpha particle(amu)
m=931;
#Calculation
deltam=2*(p+n)-alpha;
BE=deltam*m; #binding energy(MeV)
ABE=BE/4; #average binding energy per nucleon(MeV)
#Result
print "average binding energy per nucleon is",round(ABE,2),"MeV"
#importing modules
import math
from __future__ import division
#Variable declaration
n=1.008665; #mass of neutron(amu)
Li36=6.015125; #mass of Li(amu)
Li37=7.016004; #mass of Li(amu)
m=931;
#Calculation
deltam=Li36+n-Li37;
BE=deltam*m; #binding energy of neutron(MeV)
#Result
print "binding energy of neutron is",round(BE,2),"MeV"
#importing modules
import math
from __future__ import division
#Variable declaration
BEHe=4*7.0; #binding energy for He
BEH=2*1.1; #binding energy for H
#Calculation
deltaE=BEHe-(2*BEH); #energy released(MeV)
#Result
print "energy released is",deltaE,"MeV"
#importing modules
import math
from __future__ import division
#Variable declaration
n=1.008665; #mass of neutron(amu)
p=1.007276; #mass of proton(amu)
BE=160.647; #binding energy(MeV)
m=931;
#Calculation
Mx=10*(p+n)-(BE/m); #mass(amu)
#Result
print "mass is",round(Mx,3),"amu"
print "answer given in the book is wrong"
#importing modules
import math
from __future__ import division
#Variable declaration
n=1.008665; #mass of neutron(amu)
Ca41=40.962278; #mass of Ca(amu)
Ca42=41.958622; #mass of Ca(amu)
m=931;
#Calculation
deltam=Ca41+n-Ca42;
BE=deltam*m; #binding energy of neutron(MeV)
#Result
print "binding energy of neutron is",round(BE,3),"MeV"
print "answer given in the book varies due to rounding off errors"