SAT Subject Physics Practice Question 321: Answer and Explanation
17. The energy obtained in a nuclear reaction is derived from
A. mass defect.
B. binding energy.
E. all of these.
Correct Answer: E
The correct answer is (E). The sum of the individual masses of the parts of a nucleus is less than their mass when they are bound into the nucleus-producing mass defect. The mass from the mass defect is converted into the energy that holds the nucleus together and is released in fission. Fusion also produces energy when individual nuclei are forced to combine (fusion) and form new elements in a process that produces energy.