Nuclear binding energyEdexcel A-Level Physics: Mind map

Exam questions on Nuclear binding energy

1. A student is studying the nucleus of a helium-4 atom, which contains two protons and two neutrons held together by the strong nuclear force. She is comparing the mass of the nucleus with the masses of the particles that it is made from.
   Explain why the mass of the helium-4 nucleus is less than the total mass of two separate protons and two separate neutrons.2 marks
2. The deuteron, the nucleus of hydrogen-2, contains one proton and one neutron. Nuclear mass of the deuteron = 2.013553 u. Mass of a proton = 1.007276 u. Mass of a neutron = 1.008665 u. Take $1\text{ u} = 1.661 \times 10^{-27}$ kg, $c = 3.00 \times 10^{8}$ m s⁻¹ and $e = 1.60 \times 10^{-19}$ C, so that $1\text{ MeV} = 1.60 \times 10^{-13}$ J.
   Use your answer to (b) to calculate the binding energy per nucleon of the deuteron, in MeV.2 marks
3. The Sun transfers energy to space at a rate (power) of $3.8 \times 10^{26}$ W, and this energy comes from nuclear reactions in which mass is converted to energy. The mass of the Sun is $2.0 \times 10^{30}$ kg, its age is $4.6 \times 10^{9}$ years and 1 year = $3.16 \times 10^{7}$ s. Take $c = 3.00 \times 10^{8}$ m s⁻¹ and assume that the power has been constant.
   Calculate the mass that the Sun converts to energy each second.3 marks