Part I : Discussion
Roofs of houses are sometimes “blown off” during a tornado or hurricanes. Explain this using Bernoulli’s principle.
According to Bernoulli's principle, we can explain that the pressure of a fluid, which can be a liquid or a gas, decreases as the speed of a fluid increases. Using this principle, we can explain how a roof can be blown off during a storm, or lifted off. During a hurricane or tornado or any kind of wind driven storm, the fast rate in which the wind blows causes an air pressure decrease over the roof. Therefore, the pressure inside the house is greater than the outside of the house, and the greater pressure pressing up on the roof can eventually lift up the roof causing it to fly away.
Part II: Chap. 9, #12(II) Find the tension in the two wires supporting the traffic light shown in Fig. 9–46.
Chap. 9, #13.(II) How close to the edge of the 20.0-kg table shown in Fig. 9–47 can a 66.0-kg person sit without tipping it over?
(II) Figure 9–51 shows a pair of forceps used to hold a thin plastic rod firmly. If each finger squeezes with a force,what force do the forceps jaws exert on the plastic rod?
Chap. 9, #21. (II) A traffic light hangs from a pole as shown in Fig. 9–55. The uniform aluminum pole AB is 7.50 m long and has a mass of 12.0 kg. The massof the traffic light is 21.5 kg. Determine (a) the tension in the horizontal massless cable CD, and (b) the vertical and horizontal components of the force exerted by the pivot A on the aluminum pole.
Chap. 10, #17. (II) A house at the bottom of a hill is fed by a full tank of water 5.0 m deep and connected to the house by a pipe that is 110 m long at an angle of 58º from the horizontal (Fig. 10–50). (a) Determine the water gauge pressure at the house. (b) How high could the water shoot if it came vertically out of a broken pipe in front of the house?
Chap. 10, #25. (II) A spherical balloon has a radius of 7.35 m and is filled with helium. How large a cargo can it lift, assuming that the skin and structure of the balloon
have a mass of 930 kg? Neglect the buoyant force on the cargo volume itself.
Chap. 10, #32. (II) A 0.48-kg piece of wood floats in water but is found to sink in alcohol in which it has an apparent mass of 0.047 kg. What is the SG of the wood?
Chap. 10, #38. (I) How fast does water flow from a hole at the bottom of a very wide, 4.6-m-deep storage tank filled with water? Ignore viscosity.