Which of the following statements is true regarding potential energy and kinetic energy?

a. water at the top of a dam has potential energy; water falling through a dam has kinetic energy. the moving water performs work by moving the blades of turbines in the dam to generate electricity.
b. water gains kinetic energy as it falls through a dam; water uses potential energy as it moves the blades of turbines in the dam to generate electricity.
c. water gains potential energy as it falls through a dam; water uses kinetic energy as it moves the blades of turbines in the dam to generate electricity.
d. water at the top of a dam has kinetic energy; water falling through a dam has potential energy. the moving water performs work by moving the blades of turbines in the dam to generate electricity.

The correct answer is a.

Explanation:

Potential energy is energy that an object gains while at rest before falling.  When falling, it gains kinetic energy, which is the speed at which an object is falling after staying at rest.

EX: If you lay an onion on a table, it is gaining potential energy.  However, whenever the onion rolls off the table and falls to the ground, it's building up on its kinetic energy.  Eventually, according to Newton's First Law, it will come to a stop and regain its potential energy.

Just think of kinetic energy as releasing energy and potential energy as stored energy.

Hope this helps! :)

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.