An elevator moves downwards at a constant speed. When drawing the free body diagram for this motion: the upwards tension force should be shorter than the downwards gravity force
the upwards tension force should be the same as the downwards gravity force
There is no upwards tension
the upwards tension force should be longer than the downwards gravity force

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.

that tool is called an altimeter which measures your altitude which can be used to tell which atmosphere you are currently in, including the stratosphere.

hope this ! : )

3. dark matter

empty space could also be a simple vacuum