Q1: The unit of heat transfer co-efficient is

ANS:A - BTU/hr. ft²°F

1. BTU/hr: This represents British Thermal Units per hour. BTU is a unit of energy, specifically the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit. When we're discussing heat transfer, we're often interested in the amount of heat energy transferred per unit time, hence the inclusion of "per hour."
2. ft²: This stands for square feet, which is a unit of area. In the context of heat transfer, it refers to the area over which the heat transfer is occurring.
3. °F: This represents degrees Fahrenheit, which is a unit of temperature. It indicates the temperature difference driving the heat transfer process.

Putting it all together, "BTU/hr·ft²·°F" represents the amount of heat energy transferred per unit time (BTU/hr) through a given area (ft²) due to a temperature difference (°F). This unit is commonly used to quantify the rate of heat transfer in various engineering and thermal systems.