An adult person radiates heat to the surroundings at about the same rate as a 100-watt electric incandescent light bulb. What is the total amount of energy in kcal radiated to the surroundings by an adult over a 36 h period?

3097,5 kcal

Explanation:

Using the definition of power, which is work over time, where work is measured in Joules, we have that 100 watt = 100 J/sec. That means that an adult person radiates heat at the rate of 100 Joules per second. Since 1 hour has 3600 seconds, we must calculate the energy radiated in 36 hours as 100*3600*36 = 12960 kJ, where 1kJ=1000 J. Now all we need to do is to convert it in kcal. Note that 1kJ = 0.239006 kcal, so we need to multiply 12960*0.239006 = 3097,5 kcal. An adult person radiates 3097,5 kcal over a 36 h period