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Question #43693
The Question
A sample contains identical hypothetical heavy nuclei, each initially having a mass number . These nuclei undergo a continuous decay process by emitting neutrons. The binding energy per nucleon for these nuclei is given by the functional approximation , where and are positive constants, and is the instantaneous mass number. The energy released per unit decrease in mass number is defined as the instantaneous Q-value, . The decay process is statistical but can be modeled continuously such that the rate of decrease of mass number for each nucleus is directly proportional to its instantaneous Q-value, given by (where is a positive constant). Assuming , which of the following expressions represents the total power released by the sample as a function of time ?
Options
- A.
- B.
- C.
- D.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Multi-Concept_Bridge
Master problems that require linking physics and math concepts to solve complex competitive questions.
Concepts Behind This Question
Statistical Nature of Decay|Binding Energy per Nucleon Curve|Variable Force Integration
Why This Question Is Tricky
Common Mistakes
This question tests the student's ability to link macroscopic decay power to the microscopic, continuously varying mass defect.
The primary trap (Option B) catches students who treat the Q-value as a global constant calculated only at , failing to recognize that as the nucleus decays, its position on the Binding Energy curve shifts, altering the instantaneous Q-value.
Another common error (Option D) is calculating the rate of decay but forgetting that power requires multiplying this rate by the Q-value again, leading to a missing square and incorrect exponential factor.
Option C traps students who incorrectly differentiate the binding energy per nucleon instead of the total binding energy .
The problem enforces the application of energy conservation in a nuclear context via localized differentials.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Nuclei - Class 12 |
| Concept | Statistical Nature of Decay |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |