Final answer:
The smallest unit for measuring heat is the calorie (cal) in the CGS system and the joule (J) in the SI system.
Step-by-step explanation:
The smallest unit for measuring heat is the calorie (cal) in the CGS (Centimeter-Gram-Second) system, and the joule (J) in the SI (International System of Units) system.
In the CGS system, 1 cal is defined as the amount of heat needed to raise the temperature of 1 gram of water by 1 degree Celsius. In the SI system, 1 J is defined as the amount of heat needed to produce 1 newton of force over a distance of 1 meter.
For example, if you want to measure the heat generated by burning a matchstick, you can use the calorie or joule as the unit of measurement.
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