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A steel rod is 2.585 cm in diameter at 32.00°C. A brass ring has an interior diameter of 2.583 cm at 32.00°C. At what common temperature will the ring just slide onto the rod? The linear expansion coefficient of steel is 11.00 × 10-6 1/C°. The linear expansion coefficient of brass is 19.00 × 10-6 1/C°.

 

The answer should be 128 deg Celcius. But how do we get it.

 Nov 3, 2014

Best Answer 

 #1
avatar+33665 
+10

k = (1/L)*ΔL/ΔT  

 

ΔT = (1/L)*ΔL/k

 

Brass ΔT = (1/2.583)*(D-2.583)/(19*10-6)

Steel ΔT = (1/2.585)*(D-2.585)/(11*10-6)

 

By dividing the Brass by the Steel we get:

1 = (2.585/2.583)*(D-2.583)/(D-2.585)*11/19

This gives D ≈ 2.588 cm

 

Plug this back in to one of the equations above to get ΔT ≈ 96.89degC

32°C + 96.89°C = 128.89°C ≈ 129°C

.

 Nov 3, 2014
 #1
avatar+33665 
+10
Best Answer

k = (1/L)*ΔL/ΔT  

 

ΔT = (1/L)*ΔL/k

 

Brass ΔT = (1/2.583)*(D-2.583)/(19*10-6)

Steel ΔT = (1/2.585)*(D-2.585)/(11*10-6)

 

By dividing the Brass by the Steel we get:

1 = (2.585/2.583)*(D-2.583)/(D-2.585)*11/19

This gives D ≈ 2.588 cm

 

Plug this back in to one of the equations above to get ΔT ≈ 96.89degC

32°C + 96.89°C = 128.89°C ≈ 129°C

.

Alan Nov 3, 2014

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