Anotebook sitting on a desk has 19 j of potential energy. what is the total mechanical energy of the notebook?

The total mechanical energy of the notebook is 19J.

Mechanical energy is the sum of potential energy and kinetic energy.  It has no kinetic energy, because it's not moving.  So its potential energy is all the  mechanical energy it has.

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.

your answer is c! hope this : )