The binding energy of helium -4 is 28 mev. a. what is the mass of a helium nucleus (round to 5 decimal places)?

4.001805 amu

Explanation:

931 Mev = 1 amu

28 Mev = 28 / 931 Mev

= .030075 amu

Helium nucleus consists of 2 proton and 2 neutron .

Binding energy in terms of amu

= total mass of 2 neutron and 2 proton - mass of nucleus of helium

mass of nucleus of helium = total mass of 2 neutron and 2 proton -Binding energy in terms of amu

mass of 2 neutron = 2 x 1.008664 = 2.017328

mass of 2 proton = 2 x 1.007276 = 2.014552

total = 4.03188

So mass of helium nucleus = 4.03188 - .030075

= 4.001805 amu.

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west

it would stay the same