I don’t care what kind of laboratory you have. Two objects with densities of 18000000 kg/m3 is absolutely unacceptable1. You have pulleys that go the wrong way, electrons that move at the speed of light, photons that don’t, made-up equations. Apparently, you don’t know how to subtract numbers either2.
Yeah, I get it. It takes a lot of work to write these. But please, proofread? 3rd edition my ass3.