Concept to Investigate: Density, Buoyancy, Archimedes principal Materials: Salt, Eggs (2), Container MORTON Density is the mass to the volume ratio of a substance, If the density of an object is less than the density of the fluid in which it is placed, the object will float. If the density of the object is greater than the density of the fluid, it will sink. Because of the presence of dissolved salts, salt water has higher density than freshwater. Archimedes principal states that an object is buoyed by a force equivalent to the weight of the water it displaces. Knowing this, what will happen to a ship or fish as it moves from salt water to fresh water or vice versa? Place a fresh egg in a container full of tap water and record its position. Slowly stir salt in to the beaker until the egg rises and suspended above the bottom of the beaker but below the surface of water. 1) What should be added to raise the egg to the surface? 2) What should be added to cause the egg to sink to the bottom once again ? 3) Why did the egg rise when the salt was added tot he system ? 4) Will the ship ride higher in a ocean or lake ? Why? 5) Petroleum geologist and engineers often flood oil wells with salt water to increase production. Why ?

Q1): The mattress of a water bed is 2 m long by 2 m wide and 30 cm deep. A) Find the weight of the water in the mattress. B) Find the pressure exerted by the water on the floor when the bed rests in its normal position. Assume that the entire lower surface of the bed makes contact with the floor. C) What if the water bed is replaced by a 300-lb ordinary bed that is supported by four legs? Each leg has a circular cross section of radius 2 cm. What pressure does this bed exert on the floor?

A 25 m tall pipe, closed at the bottom, but open at the top to the atmosphere (which is at a pressure of 1.013 × 105 Pa), is filled to the brim with oil, resulting in the pressure at the bottom of the pipe being 2.0 × 105 Pa.  The oil is then poured out and the pipe is then filled to the brim with pure water. ii) What is the pressure at the bottom when the pipe is filled to the brim with the water? a) 2.0 × 105 Pa b) 2.5 × 105 Pa c) 3.0 × 105 Pa d) 3.5 × 105 Pa e) 4.0 × 105 Pa