Density is a derived unit. What is a derived unit and can you think of another unit that is derived?  Why is Density so important, what does it tell us? Do Trucking Companies need to know the Density of the material that they are hauling? Why would that be important?

Problem 4.50 The chain AB exerts a force of 20 lb on the door at B. (Figure 1) Figure 1 of 1 20 4 ft 3 ft A 3 ft F = 20 lb B Part A Determine the magnitude of the moment of this force along the hinged axis of the door. Express your answer to three significant figures and include the appropriate units. M₂ = Submit μA Value Units My Answers Give Up Provide Feedback Continue

A tank  that has Cylindrical shape with an inside diameter of 120 feet and a depth of 60 feet . walls and bottom  of tank are made out of concrete, walls are  is 15 inches thick , 60 feet high and the floor is 4 inches thick. The top of the tank is fiberglass and weighs 170,000 Concrete Weight = Volume of concrete ∗ unit weight of concrete  *Reinforced concrete weighs 150 #/CF.     What is the weight of the concrete tank?   What is the weight of the concrete tank?     what is the weight of the concrete tank including the roof?                    What is the total weight of the tank when it is full?                 Bearing pressure is the amount of pressure that a structure puts on the underlying soil in pounds per square feet, #/SF.        Bearing Pressure =Total weight of concrete storage tank including the waterArea of the tank floor  Calculate the bearing pressure of the tank from the previous page on the underlying soils

y A B 3 in. D C 2 in. -2 in. 1.5 in. E.