(Assume we're near the Earth's surface, so that center and gravity and center of mass are basically the same.) I've heard that the "center of gravity is not fixed when there are two pivot points as ...
I'm looking to buy a barbell/dumbbell set to start doing P90X again. I came across the Bowflex and the Powerblock adjustable sets, but they just seem so freaking expensive ($300 to start for each). ...
It seems to me they go against everything safe about lifting! Lifting with your lower back and not your legs. Image source Anyone have any thoughts on the safety and science behind them?