ma65p

I really really disagree. First thing, E= Potential energy + kinetic energy= mgh+(1/2)mv^2. Now, we are trying to get the object move by using kinetic energy only since potential energy of the object only pull it down (that also explain why the object move in projectile motion). Increasing mass will increase kinetic AND potential energy. This does not help you much while increase the mass of the object only allowed it to be pulled down faster. I really don't think increasing mass will help, unless you figure out an optimum mass that allow maximum kinetic energy. That would be great.