What to look for when buying a power tool sander.

Mike Moore converts cars in North Carolina to run on battery power.

Is GMC a good company, good strong durable equipment,? And is there a Company that makes then, That ownes them, like craftsman, dewalt, ect, plz help me,

I have just started woodworking and would like to start a cordless collection. I’ll start with the basics: drill, circular, palm sander, router. Can you all recommend a good brand. I know Dewalt is top of the line but it is out of my price range. My father has a small set of Ryobi 18v and seems happy with it. Is this a good set? Please also recommend some other necessary tools. I have several hand tools: screwdrivers, plyers, clamps.
I’ll probably start building simple projects: bookshelves, a ladder for a bunk bed, a child’s drafting table.

when going down a hill, is potential energy converted to kinetic energy or is that the other way around?

and how does conservation of energy relate to roller coasters?