Two tiny conducting spheres are identical and carry charges of - 20.0 µC and +50.0 µC. They are separated by a distance of 2.50 cm. (a) What is the magnitude of the force that each sphere experiences, and is the force attractive or repulsive? (b) The spheres are brought into contact and then separated to a distance of 2.50 cm. Determine the magnitude of the force that each sphere now experiences, and state whether the force is attractive of repulsive.

a

The force experience by the two spheres is

This force is attractive cause the charge are unlike charges

b

The force experienced by the two spheres is  

The force is repulsive because the two charges are like charges

Explanation:

From the question we are told that

   The charge on the first sphere is  

    The charge on the second sphere is  

      The distance of separation is

The electrostatic force experienced by the two spheres is mathematically represented as

Now k is the coulomb’s constant with a value of  

   So

When the sphere are brought together the charge on each sphere would be the average of the total charge and this can be mathematically evaluated as

So when they are seperated the electrostatic force experienced is  

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.