Question

Your window thermometer shows that the temperature outdoors is 89.3°f. how should you report this temperature to your friend in israel (i.e., on the celsius scale) and to your si-enthusiastic physicist neighbor (i.e., on the kelvin scale)?

Answer 1

A) Conversion from Fahrenheit to Celsius:
The relationship between the two scales is the following
$T_f = \frac{9}{5}T_c + 32$
where
$T_f$ is the temperature in Fahrenheit
$T_c$ is the temperature in Celsius

Re-arranging the formula, we find the inverse relationship:
$T_c= \frac{5}{9}(T_f-32)$
and we can use this equation to convert $T_f = 89.3^{\circ}F$ into Celsius:
$T_c = \frac{5}{9}(89.3-32)=31.7^{\circ} C$

(b) Conversion to Kelvin scale:
The conversion between Celsius scale and Kelvin scale is easier:
$T_k = T_c + 273.1$
where $T_k$ is the temperature in Kelvin. Using $T_c = 31.7^{\circ} C$, we find
$T_k = 31.7 + 273.1 = 304.8 K$