Metallic chains are hung to be dragged on ground from body of trucks carrying inflammable materials. Why?

Two similar spheres each of mass m and carrying equal charges q are hung from a common point by means of two silk threads each of length / Show that the separation x between them is given by x= ((q^(2) hatl)/(2piin_0mg))^(1//3) when the angle between the threads is very small.

Why is leaching of gold by metal cyanides carried out in the presence of oxygen? Give the chemical equation. Name the metal used as reducing agent.

In filling the gasoline tank of an aeroplane, the metal nozzle of hose from the gasoline truck is always carefully connected to the metal of the aeroplane by a wire, before the nozzle is inserted in the tank. Explain, why?

Vehicles carrying highly inflammable materials have chains hanging to the ground. Explain.

A roller of mass 600 kg is dragged by a light horizontal chain to a tractor of mass 1200kg. The opposing force of friction exerted by the ground is 800N. If the system has a forward acceleration of 2ms^-2 , calculate (i) the horizontal forward reaction of the ground on the tractor and (ii) the tension in the chain.