3.- Un barco que tiene el motor averiado es ayudado por dos remolcadores para entrar en el puerto. Cada uno de ellos tira de él con una fuerza de 10000 N y ambas forman un ángulo de 60o. Calcula el módulo de la fuerza neta que actúa sobre el barco.

F_total = 10000 N

Explanation:

For this exercise we use that the force is a vector and the best way to do the sum is that since the two tugs pull the boat with the same intensity and angle, the sum of the component of the force perpendicular to the movement becomes zero.

The components parallel to the movement of the tugs is

            ∑ F = 2 Fcos θ

let's calculate

           F_total = 2 10000 cos 60

           F_total = 10000 N

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.