Thermodynamics - shaking a bottle with liquid

[zorro]

A closed bottle contains a liquid. The bottle is shaken vigorously for 5 minutes. It is found that the temperature of the liquid is increased. Is heat transferred to the liquid? Is work done on the liquid. Neglect expansion on heating.

I think the temperature increases due to the internal viscous force of the liquid. Heat is not transferred to the liquid as the bottle is closed and no work is done the the liquid because change in volume is 0.

 

[mathman]

Shaking the bottle transfers energy (from the person or thing shaking) to the contents.

 

[zorro]

Do you mean the muscular energy of the person (shaking) is converted into kinetic energy of the liquid and consequently heat energy? So heat is transferred and work is done on the liquid.
Is it right?

 

[Andy Resnick]

Kinetic energy is definitely imparted to the fluid, but no work is done (assuming that at the end, the fluid is at rest and has not been raised or lowered). The kinetic energy is dissipated by viscous flow and converted into heat energy.

 

[Andrew Mason]

Kinetic energy is definitely imparted to the fluid, but no work is done (assuming that at the end, the fluid is at rest and has not been raised or lowered). The kinetic energy is dissipated by viscous flow and converted into heat energy.

Yes. It is a bit tricky. There is no heat flow into the liquid yet its temperature increases. From the first law: dQ = dU + dW so if dQ = 0 then dW = -dU. So work is done on the liquid. It is just that the work is converted to heat.

This is similar to the Joule paddle experiment.

AM

 

[zorro]

There is no heat flow into the liquid yet its temperature increases. From the first law: dQ = dU + dW so if dQ = 0 then dW = -dU. So work is done on the liquid. It is just that the work is converted to heat.

This is similar to the Joule paddle experiment.

AM

Thankyou!