Basic Statistics for Epidemiology: Prevalence vs Incidence. In short, epidemiology is sort of the who what, when, why, how and where of disease. It doesnât involve any experimentation or clinical trials, so it is really of interest to public health, because it is just about what happens.
So if a queen-sized waterbed with a bladder-type mattress holds roughly 130 gallons of water that weighs in at 1,084 pounds plus the weight of the frame and two people.o keep the math simple let s assume that the mattress, frame and two adults weighs 1,300 pounds and that the bed assembly measures six feet by six feet taking up a total of 36 square feet of floor space. If we divide the weight of the bed by 36 the square footage-that gets us to 36 pounds per square foot.
The buoyancy force is equal to the volume of water it displaces multiplied by 62.4 lbs. per cubic foot (the density of water). So if the boat displaces 20 cubic feet of water with it's hull or shape it can hold 20 x 62.4 = 1248 lbs. of self weight plus cargo. Obviously there should be a factor of safety on that.  In summary, a boat needs two things to float on water: Gravity and buoyancy force.