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Question #77078
The Question
A solid sample of mass and unknown specific heat is heated to an initial measured temperature . It is then dropped into a calorimeter containing a liquid, with the system having a combined heat capacity . The initial measured temperature of the calorimeter and the surrounding environment is . The mixture reaches a maximum measured temperature after a time . During this mixing phase, heat is lost to the surroundings according to Newton's Law of Cooling, with a cooling constant (in ). All temperatures are measured using a thermometer whose scale is printed on a metal strip with a coefficient of linear expansion . The thermometer is perfectly calibrated at , and the true temperature is strictly proportional to the absolute length of the thermometric liquid column. Assuming is very small such that terms of order and higher can be neglected, determine the specific heat of the sample.
Options
- A.
- B.
- C.
- D.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Variable_Constraint
Develop pure symbolic logic skills by mastering algebraic constraints without relying on numerical data.
Concepts Behind This Question
Zero Error Correction|Calorimetry with Heat Loss|Thermal Expansion of Area and Volume|Binomial Approximation
Why This Question Is Tricky
Examiner Levers
Visualization Stress
Requires mental rotation or 3D mapping (Optics/Geometry/Vectors).
Difficulty Boost : +4Variable Manipulation
Algebraic solutions only (No numbers); tests pure symbolic logic.
Difficulty Boost : +4Common Mistakes
This question tests two distinct, nested physical traps.
First, students often misapply the thermal expansion correction by assuming the error scales with the temperature difference directly (i.e., ), which leads to the incorrect term in Option B.
The correct approach requires expanding the squares of individual temperatures, revealing that the final mixture temperature elegantly cancels out of the correction factor.
Second, it tests the application of Newton's Law of Cooling during a dynamic mixing phase; students who fail to use the average temperature difference will incorrectly use the maximum difference, leading to the unhalved term in Option C.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Units and Measurements - Class 11 Part 1 |
| Concept | Zero Error Correction in Instruments |
| Difficulty | 8 |
| Cognitive Load | 8 |
| Target Solve Time | 180 sec |
| Access | Free |