Q.

A metal rod Aof 25 cm length expands by 0.050 cm when its temperature is raised from 0°C to 100°C. Another rod B of a different metal of length 40 cm expands by 0.040 cm for the same rise in temperature. A third rod C of 50 cm length is made up of pieces of rods A and B placed end to end expands by 0.03 cm on heating from 0°C to 50°C. Find the difference of the lengths of each portion of the composite rod (in cm)

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Detailed Solution

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 From Δl=lαΔθ we have 0.05=25αA(100)

αA=0.00002 per °C

0.04 =40αB(100)

αB=0.00001 per °C

In third case let l is the length of rodA. Then length of rodB will be (50l)cm

Δl=Δl1+Δl2 or 0.03=l(0.00002)(50)+(50l)(0.00001)(50)

Solving we get l=10 cm and 50l=40 cm

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A metal rod Aof 25 cm length expands by 0.050 cm when its temperature is raised from 0°C to 100°C. Another rod B of a different metal of length 40 cm expands by 0.040 cm for the same rise in temperature. A third rod C of 50 cm length is made up of pieces of rods A and B placed end to end expands by 0.03 cm on heating from 0°C to 50°C. Find the difference of the lengths of each portion of the composite rod (in cm)