Which of the following is not a source of energy used by living things? a. chemical energy b. solar energy c. mechanical energy d. wind energy

Option-(D):  Wind energy.

Explanation:

Wind energy:

The  wind energy is a form of solar energy which is used to transmit the amount of energy present in the molecules of the solar rays which originates from the Sun surface moving towards the planet earth. As these molecules are carried in air from one point inside the earth's atmosphere in form of air.

As, there are different machinery and advanced form of structures being made to catch these molecules, and then turn them into the mechanical energy, and at last the electrical form of energy is obtained as a result.

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.

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