Q23 of 27 Page 82

We would like to make a vessel whose volume does not change with temperature (take a hint from the problem above). We can use brass and iron (βvbrass = 6 × 10-5/K and βviron = 3.55 ×10-5 / K) to create a volume of 100 cc. How do you think you can achieve this?

Here, we can have a bimetallic vessel with iron on the outside and brass on the inside as brass expands more than iron.

The change in volume of both the metals should be same.






Now,





So, the volume of the brass vessel should be 144.9 cc and that of iron vessel should be 244.9 cc.


More from this chapter

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21

One day in the morning, Ramesh filled up 1/3 bucket of hot water from geyser, to take bath. Remaining 2/3 was to be filled by cold water (at room temperature) to bring mixture to a comfortable temperature. Suddenly Ramesh had to attend to something which would take some times, say 5-10 minutes before he could take bath. Now he had two options: (i) fill the remaining bucket completely by cold water and then attend to the work, (ii) first attend to the work and fill the remaining bucket just before taking bath. Which option do you think would have kept water warmer? Explain.

22

We would like to prepare a scale whose length does not change with temperature. It is proposed to prepare a unit scale of this type whose length remains, say 10 cm. We can use a bimetallic strip made of brass and iron each of different length whose length (both components) would change in such a way that difference between their lengths remain constant. If αiron 1.2 X 10-5/ K and αbrass 1.8 X 10-5 /K , what should we take as length of each strip?

24

Calculate the stress developed inside a tooth cavity filled with copper when hot tea at temperature of 57o C is drunk. You can take body (tooth) temperature to be 37o C and α = 1.7× 10-5 /o C, bulk modulus for copper = 140 × 10 9 N/m2.

25

A rail track made of steel having length 10 m is clamped on a railway line at its two ends (Fig 11.3). On a summer day due to rise in temperature by 20° C, it is deformed as shown in figure. Find x (displacement of the center) if αsteel = 1.2× 10-5 /°C.

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