Ablock of mass m is dropped from the fourth floor of an office building and hits the sidewalk below at speed v. from what floor should the block be dropped to double that impact speed?

The substances that are necessary for producing of certain hormones and that store and transport vitamins

The magnitude of the poynting vector of a planar electromagnetic wave has an average value of 0.939 w/m^2 . the wave is incident upon a rectangular area, 1.5 m by 2.0 m, at right angles. how much total electromagnetic energy falls on the area during 1.0 minute?

What is the freezing point of radiator fluid that is 50% antifreeze by mass? kf for water is 1.86 ∘c/m.