Answer
The answer and procedures of the exercise are attached in the following archives.
Step-by-step explanation:
You will find the procedures, formulas or necessary explanations in the archive attached below. If you have any question ask and I will aclare your doubts kindly.
Answer:
The new force is 1/4 of the previous force.
Explanation:
Given
---- 
--- 
Required
Determine the new force
Let the two particles be q1 and q2.
The initial force F1 is:
--- Coulomb's law
Substitute 2 for r1


The new force (F2) is

Substitute 4 for r2



Substitute 


The new force is 1/4 of the previous force.
Answer:
The tangential speed of the tack is 6.988 meters per second.
Explanation:
The tangential speed experimented by the tack (
), measured in meters per second, is equal to the product of the angular speed of the wheel (
), measured in radians per second, and the distance of the tack respect to the rotation axis (
), measured in meters, length that coincides with the radius of the tire. First, we convert the angular speed of the wheel from revolutions per second to radians per second:


Then, the tangential speed of the tack is: (
,
)


The tangential speed of the tack is 6.988 meters per second.