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

co2reflects heat radiation back to earth buning coal and oil emits co2 globe warms

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.