 University Physics Volume 2

# Problems

### 1.2Thermometers and Temperature Scales

43 .

While traveling outside the United States, you feel sick. A companion gets you a thermometer, which says your temperature is 39. What scale is that on? What is your Fahrenheit temperature? Should you seek medical help?

44 .

What are the following temperatures on the Kelvin scale?

(a) $68.0°F,68.0°F,$ an indoor temperature sometimes recommended for energy conservation in winter

(b) $134°F,134°F,$ one of the highest atmospheric temperatures ever recorded on Earth (Death Valley, California, 1913)

(c) $9890°F,9890°F,$ the temperature of the surface of the Sun

45 .

(a) Suppose a cold front blows into your locale and drops the temperature by 40.0 Fahrenheit degrees. How many degrees Celsius does the temperature decrease when it decreases by $40.0°F40.0°F$? (b) Show that any change in temperature in Fahrenheit degrees is nine-fifths the change in Celsius degrees

46 .

An Associated Press article on climate change said, “Some of the ice shelf’s disappearance was probably during times when the planet was 36 degrees Fahrenheit (2 degrees Celsius) to 37 degrees Fahrenheit (3 degrees Celsius) warmer than it is today.” What mistake did the reporter make?

47 .

(a) At what temperature do the Fahrenheit and Celsius scales have the same numerical value? (b) At what temperature do the Fahrenheit and Kelvin scales have the same numerical value?

48 .

A person taking a reading of the temperature in a freezer in Celsius makes two mistakes: first omitting the negative sign and then thinking the temperature is Fahrenheit. That is, the person reads $–x°C–x°C$ as $x°Fx°F$. Oddly enough, the result is the correct Fahrenheit temperature. What is the original Celsius reading? Round your answer to three significant figures.

### 1.3Thermal Expansion

49 .

The height of the Washington Monument is measured to be 170.00 m on a day when the temperature is $35.0°C.35.0°C.$ What will its height be on a day when the temperature falls to $−10.0°C−10.0°C$? Although the monument is made of limestone, assume that its coefficient of thermal expansion is the same as that of marble. Give your answer to five significant figures.

50 .

How much taller does the Eiffel Tower become at the end of a day when the temperature has increased by $15°C?15°C?$ Its original height is 321 m and you can assume it is made of steel.

51 .

What is the change in length of a 3.00-cm-long column of mercury if its temperature changes from $37.0°C37.0°C$ to $40.0°C40.0°C$, assuming the mercury is constrained to a cylinder but unconstrained in length? Your answer will show why thermometers contain bulbs at the bottom instead of simple columns of liquid.

52 .

How large an expansion gap should be left between steel railroad rails if they may reach a maximum temperature $35.0°C35.0°C$ greater than when they were laid? Their original length is 10.0 m.

53 .

### Footnotes

• 1JW Vezina, “An examination of the differences between two methods of estimating energy expenditure in resistance training activities,” Journal of Strength and Conditioning Research, April 28, 2014, http://www.ncbi.nlm.nih.gov/pubmed/24402448
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