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Question #43932
The Question
A block of mass is released from rest and slides down a rough inclined plane of angle . A small generator attached to the block produces an electrical power , where is the instantaneous velocity of the block and . This power is entirely dissipated as heat by a coil embedded in the bottom surface of the block. The coefficient of kinetic friction between the block and the incline decreases with the dissipated power as , where and . Assuming the thermal response is instantaneous, what is the kinetic energy of the block after it has slid a distance down the incline? (Take )
Options
- A.
- B.
- C.
- D.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Intuition_Breaker
Train your brain to resist "obvious" answers that are designed to deceive your intuition.
Concepts Behind This Question
Cell EMF vs Terminal Voltage|Kinetic Friction Transition|Binomial Approximation
Why This Question Is Tricky
Common Mistakes
The core trap tests the student's ability to handle dynamically coupled non-conservative forces.
A common mistake is treating the work done by friction as a simple macroscopic average or ignoring the velocity dependence entirely (yielding 25 J).
Another trap is a sign error when substituting the decreasing friction into the net force equation, leading to an exponentially decaying acceleration profile instead of an exponentially growing one (yielding 25(1 - e^-1) J).
This question forces the application of the Work-Energy Theorem in its differential form (dK = F_net dx) and tests the mathematical translation of a physical feedback loop (velocity -> power -> heat -> friction -> acceleration -> velocity).
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Current Electricity - Class 12 |
| Concept | Cell EMF vs Terminal Voltage |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |