Why isn't nuclear fusion used to generate electrical energy in power plants? a. it requires extremely high temperatures. b. it releases energy per gram than coal does. c. it generates radioactive waste. d. it uses a very rare element.

2) a cubical block of stone is lowered at a steady rate into the ocean by a crane, always keeping the top and bottom faces horizontal. which one of the following graphs best describes the buoyant force b on this block as a function of time t if the block just enters the water at time t = 0 s?