Quick I'll Mark it Brainliest Which of the following statements is true? A. Burning air and gasoline in an engine changes chemical energy into mechanical energy. B. Friction causes molecules to vibrate more slowly. C. It is impossible to change mechanical energy into mechanical energy. D. Most heat energy is easily recovered and used for useful actions.

A, B and C

Explanation:

The A, B and C look most probable. Heat energy flared to atmosphere might not be recovered. It could end up heating up the atmosphere.

where are the vectors ?

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.