. A small sphere of radius r falls from rest in a viscous


liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to

A: r5

B: r3

C: r4

D: r2

 

Best Answer

Explanation: 

Rate of heat generation due to viscous forces can be given by

P = Fv

Where P is the rate of heat generation, F is the force and v is the velocity.  

When spherical ball attains terminal velocity (v0), the rate of heat generation 

P = Fv0

small sphere

Hence the rate of production of heat when the sphere attains its terminal velocity, is proportional to r5.

Final Answer:

Rate of production of heat when the sphere of radius r attains its terminal velocity, is proportional to r5. Hence the correct option is option (A ) .

 

 

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