x = linspace(0,4);

E = 5.5*sqrt(1-x/4);

hold off;

plot(x,E);

grid on;

xlabel('Distance traveled in cm');

ylabel('Kinetic energy of \alpha-particle in MeV');

title('Energy loss of alpha particle in air at STP');

hold on;

plot(1,5.5*sqrt(3/4),'o','markersize',10);

text(1.12,4.8,'(1cm, 4.76MeV)');