what is relative velocity in one dimension if va and vb are the velocities of two body a and b respectively then prove vab=va -vb

Relative velocity is nothing but the velocity of one body with respect to the velocity of some other body.  

Explanation:

Relative velocity may be defined as the rate at which the change of separation takes place between any two object.The relative velocity of any object A w.r.t. another object B when they are in motion is nothing but the rate of change of their position from one another.

Now, let the velocity of object A be  

         and velocity of object B is

Therefore, relative velocity of a object A when compared to the velocity of object B is given by .

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.

answer is slate

hope this