Question

Positively charged point objects 1,2, and 3 are pictured above located exactly on meter marks. Object 1 exerts a force of 48 N on object 2. How much force does object 1 exert on object 3?

• A. 48 N
• B. 24 N
• C. 12 N
• D. 6 N
• E. 3 N

Answer 1

Answer: (E)

3 N

We assume that the all point objects have positive charge, $q$

Thus, by Coulomb's law, the force exerts on 2 due to 1 is $F_{21}=\frac{kqq}{2^2}$

Given, $F_{21}=48N$ so, $k{q}^2=4\times 48$

Thus, force on 3 due to 1 is $F_{31}=\frac{k{q}^2}{8^2}=\frac{4\times 48}{64}=3N$