What is a possible state for an object in the absence of a net force?

Alightning strike consists of charge moving from a cloud to the ground . in one particular case, the electrons in a lightning strike are confined to travel within a radius of 1.5 m and to move at a speed of 5.0 x 10 m/s. if the density of electrons in the strike is 10'15 electrons/m what current is carried by the lightning ?

Molten iron fills a mould, which has a volume of 200 cm cubed. calculate the volume when the iron cools and solidifies.

What happens in a global convection cell