Question

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?

Answer 1

An adult person radiates heat to the surroundings at about the same rate as a 100-watt electric incandescent light bulb. The total amount of energy in kcal radiated by an adult over a 36-hour period is 3100 kcal.

Step-by-step explanation:

An adult person radiates heat to the surroundings at about the same rate as a 100-watt electric incandescent light bulb.

To calculate the total amount of energy in kcal radiated by an adult over a 36-hour period, we need to first convert the power from watts to kilocalories.

One kilocalorie is equal to 0.001163 watt-hours.

So, the energy radiated by the adult in kilocalories can be calculated as:

Energy (kcal) = Power (kW) x Time (hours)

Energy (kcal) = 0.1 kW x 36 hours

= 3.6 kWh

= 3100 kcal.

Answer 2

3097,5 kcal

Step-by-step 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