2) Weight & Mass : what is the difference between the two? What does it mean to be weightless

The weight of an object is a measure of the force exerted on the object by gravity, or the force needed to support it whereas mass is the amount of matter contained in a body. The SI unit of weight is Newton whereas the SI unit of mass is Kilogram.

No idea about weightless maybe the objects not apparently acted on by gravity.

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force