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EF 152 Exam #1, Fall, 2014 Page 1 of 6 Name: Section: ________ It’s on your seating label! Instructions • Do not open the exam until instructed to do so. • Do not leave if there is less than 5 minutes to go in the exam. • When time is called, immediately stop writing, remain seated, and pass your exam to the center aisle. • Do not stand up or leave until all exams have been collected. • Working after time is called results in an automatic 10 point deduction. Guidelines • Assume 3 significant figures for all given numbers unless otherwise stated • Show all of your work – no work, no credit • Write your final answer in the box provided Stress and Strain Stress = Strain = = = Bernoulli’s Equation $ & ∆ Lift ≅ '-+( ! WX Density of Water 3 62.4 lb/ft 3 1000 kg/m Atmospheric Pressure 101.3 kPa 14.7 psi Conversions 3 1 ft = 7.48 gal 3 1 m = 1000 L Uniform Circular Motion Mass density 2 3 Weight density 5 3 = 6789( Poiseuille’s Equation uv = DE 9b gb = 1.0 × 10 Pa ∙ s AK wB < = 9t & Specific gravity (relative density) m `= ;< = ([email protected] A?B ) ( = t9 mnopqr or U B s snopqr NY P [\ (]^_ = Z Stokes’ Law 8F STB N∙YP Fluids p – pressure h – height ρ – mass density v – velocity K – empirical constant A – area d – depth "# – pressure on top of fluid := = (=Z < = ')1 ! <B Satellites Buoyant force 0 <B 2P Kepler’s Third Law VB (&;)B & " = '). + "# = [email protected] 2B O = 6.674 × 10A$$ Pressure in a fluid Factor of Safety (FS) =O )=O ($ +$ = (& +& = 4= N & Continuity ∆ = '= Universal Law of Gravitation $ "$ + '($& + ')ℎ$ = "& + '(&& + ')ℎ& &N∙YP <P &; a = 6.38 × 10e m = 5.97 × 10&j kg Ellipse eccentricity: x= &W semi-major axis: u= (any curve) Constant acceleration $ ~ = ~# + (# • + u• & & ( = (# + u• ∆~ = <yz{ A<y|} w B Aw€B &W <yz{ [<y|} & EF 152 Exam #1, Fall, 2014 [This page intentionally left blank] Page 2 of 6 EF 152 Exam #1, Fall, 2014 Page 3 of 6 1. (2 pts) The volume of a 10 lb bowling ball is 0.186 ft3. Will this bowling ball sink or float in water? a. sink b. float c. need more information 2. (2 pts) Object A weighs 50 lb. Object B weighs 25 lb. How do their respective escape velocities compare? a. vA = ¼ vB b. vA = ½ vB c. vA = vB d. vA = 2 vB e. vA = 4 vB 3. (2 pts) In a Venturi tube, how does the pressure in the restriction (p2) compare to the inlet pressure (p1)? a. p2 > p1 b. p2 = p1 c. p2 < p1 4. (8 pts) A satellite orbits the earth such that its period is 18 hours (64800 sec). Determine the height of the satellite above the earth’s surface. EF 152 Exam #1, Fall, 2014 Page 4 of 6 5. (6 pts) Determine the cross-sectional area of a 20 ft long, steel column that shortens 0.03 inches under a 5000 lb load. Esteel = 29x106 psi. 6. (16 pts) An L-bracket is supported by a pin at A and a cable at B as shown. Determine the x-component of the reaction force at A. A separate, complete FBD is required for full credit. y cable 50° x B 4 ft 16 lb A 2 ft 3 ft EF 152 Exam #1, Fall, 2014 Page 5 of 6 7. (16 pts) Chris takes a break while pushing a 75 lb bookshelf up a ramp as shown. Determine the magnitude of the force P required to keep the bookshelf from tipping down the ramp. A separate, complete FBD is required for full credit. CG 10° P 25° 8. (16 pts) An 8 ft x 8 ft x 2 ft floating dock weighs 3500 lb and is anchored to the bottom of a lake by a steel cable with a cross-sectional area of 0.15 in2 and an ultimate strength of 270x103 psi. Due to flooding, the dock is completely submerged. Determine the factor of safety of the cable. A separate, complete FBD is required for full credit. water level DOCK cable lake bottom EF 152 Exam #1, Fall, 2014 Page 6 of 6 9. (16 pts) A warehouse is 5.5m tall and equipped with a fire sprinkler system. The system delivers water at a rate of 0.02 m3/s. The main pipe leaving the pump has an area of 6.4x10-3 m2 and the pipe delivering water to the sprinklers has an area of 1.2x10-3 m2. Determine the pressure provided by the pump such that water is delivered to the sprinklers at 350 kPa. to sprinklers Pump 10. (16 pts) A glass marble (radius = 0.015m) falling through olive oil reaches a terminal velocity of 4.56 m/s. j Determine the mass density of olive oil. Vsphere = 79 K ; FBD required for full credit K 'glass = 2200 kg/m3 ; 8 olive oil = 0.138 Pa·s