EVERYDAY SCIENCE

Detailed explanation-1: -A British thermal unit (Btu) is a measure of the heat content of fuels or energy sources. It is the quantity of heat required to raise the temperature of one pound of liquid water by 1 degree Fahrenheit at the temperature that water has its greatest density (approximately 39 degrees Fahrenheit).

Detailed explanation-2: -The British thermal unit, Btu, is another unit of heat used in the United States. One Btu is the amount of heat required to raise the temperature of 1 lb of water by 1°F.

Detailed explanation-3: -The centigrade heat unit (CHU) is the amount of heat required to raise the temperature of one pound of water by one Celsius degree. It is equal to 1.8 BTU or 1, 899 joules.

Detailed explanation-4: -The calorie (or gram-calorie) is the amount of energy required to raise the temperature of one gram of water from 14.5 to 15.5 °C; the BTU is the amount of energy required to raise the temperature of one pound of water from 63 to 64 °F. One BTU is approximately 252 calories.

Detailed explanation-5: -The calorie was originally defined as the amount of heat required at a pressure of 1 standard atmosphere to raise the temperature of 1 gram of water 1° Celsius. Since 1925 this calorie has been defined in terms of the joule, the definition since 1948 being that one calorie is equal to approximately 4.2 joules.