While skateboarding at 19 km/h, alana throws a tennis ball at 11 km/h to her friend oliver. if alana is the reference frame, the speed of the tennis ball is km/h.

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.

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement