# If two charged bodies are connected by a string will the tension be F or 2F?(F is the force of repulsion between them) [duplicate]

If two charged bodies are connected by a string will the tension be F or 2F?(F is the force of repulsion between them)

## marked as duplicate by garyp, user36790, Qmechanic♦Nov 27 '16 at 17:24

• There will be Tension $T=F$ from both sides of the string, on each side where the charges are attached. However. I do wonder what the total force experienced by the string is. 2F or zero? – Kalpak Gupta Nov 27 '16 at 15:42
• Net force on the string is zero. Tensile stress at any point in the string is $F/A$ with $A$ the cross section of the string. – Pirx Nov 27 '16 at 15:55
• Possible duplicate: physics.stackexchange.com/q/41291/50583 – ACuriousMind Nov 27 '16 at 15:59

If the electrostatic repulsive force is given by $$F=\frac{Q_1Q_2}{4\pi\epsilon_0r^2}$$ and you consider one body held back by the string, the force exerted by the string on the body will be $-F$ so that there is a zero total force on the body. Thus, according to Newton's 3rd law, at any cross section of the string the sum of the positive and negative force $F$ gives a zero total force $F_\textrm{tot}=F-F=0.$ Thus the tension in the string is simply the repulsive force $F$ between the bodies