HW33  Due 25 April

1.      An office window has dimensions 3.4 m by 2.1 m.  As a result of a storm front passage, the outside air pressure drops to 0.96 atm, but inside the pressure is held at 1.0 atm.. What net force pushes out on the window?     Solution

2.     Calculate the hydrostatic difference in blood pressure between the brain and the foot in a person who is 1.83 m tall.  The density of blood is 1.06 x 103 kg/m3.

Solution

3.     A piston of small cross sectional area a is used in a hydraulic press to exert a small force f on the enclosed liquid.  A connecting pipe leads to a large piston of cross sectional area A (see Figure).  (a) What force magnitude F will the larger piston sustain without moving?  (b) If the small piston has a diameter of 3.80 cm and the large piston a diameter of 53.0 cm, what force magnitude on the small piston will balance a 20 kN force on the large piston?  (c) Through what distance must the large piston be moved to raise the small piston a distance of 0.85 m?

4.     An iron anchor of density 7870 kg/m3 appears 200N lighter when in water than in air.  (a)  What is the volume of the anchor?  (b) How much does it weigh in air?

Solution

5.     Water is moving with a speed of 5.0 m/s through a pipe with cross sectional area of 4.0 cm2.  The pipe descends 10 m and grows in cross sectional area to 8.0 cm2.  (a) What is the speed of the water at the lower level?  (b) If the pressure at the upper level is 1.5 x 105 Pa, what is the pressure at the lower level?    Solution