1. Entropy of a system may decrease if it is not isolated. Which of the systems

Question

1. Entropy of a system may decrease if it is not isolated. Which of the systems described below changes from a less to a more ordered state? a)butter melts b)water boils c)an engine cools d) air expands at constant temperature e) orange juice and carrot juice are mixed together

2. When you stand directly between 2 speakers that emit the same single frequency out of phase, you hear no sound. Sound is maximum when you step 0.5m towards one speaker, away from the other. What is the largest possible wavelength of this frequency? a)0.25m b)0.5m c)1.0m d)2.0m e)4.0m

Explanation / Answer

c) an engine cools is a case of decreasing entropy because cooling is the process which shifts the hot molecules which are having more kinetic energy to their normal states which is their order state. SO an engine cools is decrease in entropy.

a) butter melts is increase of entropy , because liquid is more disordered than solid.

b) water boils is increase of entropy because boiling of water mean it is converting to gaseous state which is of course increase of entropy.

d) at cosntatn temprature entropy is proportional to the volume. If gas is expanding then volume increases so therefore entropy increase too.

2) The largest possible wavelenth will be 0.25m. There is inverse square relationship between frequancy and intentiy. If intesity is maximum when the distance is o.5m then the wavelenth will increase by o.25m.

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