The specific heat capacity of glass can be calculated using the heat transfer formula Q = mcΔT, and with the data provided, it results in a specific heat capacity of 0.1 BTU/lb°F for the glass.
The student is asking about the specific heat capacity of glass, which can be found by using the information that two British Thermal Units (BTUs) of heat raised the temperature of the glass from 70°F to 90°F. Specific heat capacity is defined as the amount of heat energy required to raise the temperature of one pound of a substance by one degree Fahrenheit.
To solve this problem, we use the formula for heat transfer: Q = mcΔT, where Q is the heat energy in BTUs, m is the mass of the object in pounds, c is the specific heat capacity, and ΔT is the change in temperature in degrees Fahrenheit. Assuming the mass of the glass is 1 pound (as not given in the question), we can rearrange the formula to solve for c: c = Q / (mΔT). Plugging in the numbers, we have:
Q = 2 BTUs (given)
m = 1 lb (assuming for calculation)
ΔT = 90°F - 70°F = 20°F
Therefore, the specific heat capacity of the glass is c = 2 BTUs / (1 lb * 20°F) = 0.1 BTU/lb°F.