Answer:
[tex]7.73544\times 10^{-21}kgm/sec[/tex]
Explanation:
We have given mass of helium nucleus [tex]m=6.68\times 10^{-27}kg[/tex]
Velocity of helium nucleus [tex]v=0.386c=0.386\times 3\times 10^{8}m/sec=1.158\times 10^{8}m/sec[/tex]
Momentum of the helium nucleus is given by [tex]P=mv[/tex] where m is mass and v is velocity
So [tex]P=mv=6.68\times 10^{-27}\times 1.158\times 10^{8}=7.73544\times 10^{-21}kgm/sec[/tex]