Charges Q1 and Q2 exert repulsive forces of 10N on each other. What is the repulsive force when their separation is decreased so that their final separation is 80% of their initial separation.(adsbygoogle = window.adsbygoogle || []).push({});

A. 16N

B. 12N

C. 10N

D. 8.0N

E. 6.4N

I think you have to use the equation F = K (Q1)(Q2)/ r^2 and multiply the distance (r) by .80 but I'm not sure how you calculate the force if you also have another unknown in the equation (r).

Another question..

An electron is moving horizontally east in an electric field that points vertically upward. The electric force on the electron is

A.zero

B.upward

c.downward

d.to the west

e. to the east

My thoughts are that it is B. upward. The reason for my thinking is because I am pretty sure the electric field points in the same direction as the force but I am not quite sure if my thinking is right.

any help would be really appreciated....

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# Homework Help: Force and Electric Field

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