I have made a thermometer which measures temperature by the compressing and expanding of gas in a piston. I have measured that at 100 degrees C the volume of the piston is 20 L. What is the temperature outside if the piston has a volume of 15 L? What would be appropriate clothing for the weather?

The temperature outside is 75 degrees C. Appropriate clothing for this weather would be light layers such as a t-shirt and a light jacket, shorts or pants, and closed-toe shoes.

To calculate the temperature outside, we can use Charles's Law, which states that the volume of a gas is directly proportional to its temperature when pressure and amount of gas are constant.

To find the temperature outside when the piston has a volume of 15 L, we can set up a proportional relationship using the initial temperature and volume:

(Volume1 / Temperature1) = (Volume2 / Temperature2)

Substituting the given values:
(20 L / 100 °C) = (15 L / Temperature2)

To solve for Temperature2, we can cross-multiply and solve for it:

Temperature2 = (15 L * 100 °C) / 20 L

Temperature2 = 75 °C

Therefore, the temperature outside is 75 degrees Celsius.

As for appropriate clothing for the weather, 75 degrees Celsius is extremely hot and potentially dangerous. It is well above boiling temperatures and could cause severe burns. If the readings are accurate, it is likely an error in the measurement or calculation. For such extreme temperatures, it would be best to seek shade, stay hydrated, and avoid direct exposure to the heat.

To determine the temperature outside when the piston volume is 15 L, we can use the principle of the ideal gas law which states:

PV = nRT

Where:
P = Pressure
V = Volume
n = Number of moles
R = Ideal gas constant
T = Temperature in Kelvin

Assuming the pressure remains constant, we can rearrange the equation to solve for temperature (T). By comparing the two scenarios, we can find the relationship between the volumes and temperatures:

(P1 * V1) / T1 = (P2 * V2) / T2 [where P1, V1, T1 refer to the initial conditions and P2, V2, T2 refer to the new conditions]

Since we are given that at 100 degrees Celsius the volume of the piston is 20 L, and we want to find the temperature when the volume is 15 L, we can substitute the values into the equation and solve for T2:

(1 atm * 20 L) / (100 + 273.15 K) = (1 atm * 15 L) / T2

Simplifying the equation:

20 / (100 + 273.15) = 15 / T2

T2 = (15 / 20) * (100 + 273.15)

T2 = 338.725 K

Converting the temperature to degrees Celsius:

T2 = 338.725 - 273.15 = 65.575°C

Therefore, the temperature outside would be approximately 65.6°C.

As for appropriate clothing for the weather, 65.6°C is an extremely high temperature and would be considered well above the boiling point of water. It is likely unsafe to be outside under these conditions, as it could cause severe burns or harm to the human body. However, assuming you meant a lower temperature value, please provide the correct temperature so I can suggest appropriate clothing options.