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2 EXAM 2 PHYS 103 VERSION A SPRING 07 NAME: SECTION As a student at NJIT I, will conduct myself in a professional manner and will comply with the provisions of the NJIT Academic Honor Code. I also understand that I must subscribe to the following pledge on major work submitted for credit as described in the NJIT Academic Honor Code: On my honor, I pledge that I have not violated the provisions of the NJIT Academic Honor Code. The exam is closed book and closed notes. Choose the answer that is closest to the given answer. ρ w =1000 kg/m 3 p = F/A; p h = ρgh; 1 atm = x10 5 Pa, F B = ρgv A 1 v 1 = A 2 v 2 Av -volume flow rate, Mass flow rate = Avρ p 1 + 1/2ρv ρgh 1 = p 2 + 1/2ρv ρgh 2 flow in horizontal pipe: p 1 + 1/2ρv 1 2 = p 2 + 1/2ρv 2 2 T( 0 C) = 9 5 [T( 0 F) - 32]; T( 0 F) = 5 9 T( 0 C) + 32; T(K) =[T( 0 C) + 273] L - L 0 =α L 0 (T-T 0 ); A - A 0 =2α L 0 (T-T 0 ); V - V 0 = β V 0 (T-T 0 ) V - V 0 =3α V 0 (T-T 0 σ = Yα (T-T 0 ) ρ = m ; A circle = πr 2 1 m = 100 cm V cube = a 3 4 V sphere = π R 3 V 3 V cyl = πr 2 L 1m = 100 cm 1 kg = 1000 g

3 EXAM 2 PHYS 103 VERSION A SPRING To obtain the absolute pressure from the gauge pressure: A) subtract the atmospheric pressure B) add atmospheric pressure C) subtract 273 D) add 273 E) convert to N/m 2 2. A cylindrical submarine with mass 20 x 10 5 kg, radius of 2.75 m and length of 100 m is anchored to the bottom of a channel as shown schematically in the figure. What is the tension in the cable assuming the submarine is totally submerged? A) 3.7x10 6 N B) 4.8x10 7 N C) 7.6x10 6 N D) 24x10 4 N E) can t tell 3. A sample of unknown material appears to weigh 300 N in air and 200 N when immersed in water. The density of the material is closest to A) 1200 kg/m 3 B) 2000 kg/m 3 C) 3000 kg/m 3 D) 4000 kg/m 3 E) 6500 kg/m 3 4. A hydraulic press is designed to lift maximum weight of N when 120 N force is applied to the smaller piston The radius of the smaller piston is 2.5 cm. What is the radius of the larger piston? A) 25 cm B) 35 cm C) 49 cm D) 58 cm E) 65 cm 5. A sump pump has an outflow in the form of a cylindrical pipe with a radius of 1.5 cm. If water streams steadily at 7 m/s in the pipe, what is the rate at which mass is leaving the pipe? A) 0.5 kg/s B) 2.2 kg/s C) 3.0 kg/s D) 4.9 kg/s E) 8.8 kg/s 6. An air condition system uses a cylindrical air duct to replenish the air in a room of volume 280 m 3 every 8 min. The air flows in the duct at 5 m/s. What is the cross-section area of the air duct? A) 0.09 m 2 B) 0.12 m 2 C) 0.24 m 2 D) 0.38 m 2 E) 0.62 m 2 2

4 EXAM 2 PHYS 103 VERSION A SPRING If wind (density of air =1.29 kg/m 3 ) blows at 30 m/s parallel to a flat roof having an area of 475 m 2, what is the force exerted on the roof? A) 2.76x10 5 N, up B) 8.75x10 5 N, down C) 4.26x10 6 N, up D) 6.16x10 6 N, down E) 1.23x10 7 N, up 8. The weather outside is frightful. The temperature is C. What is the corresponding temperature in the Fahrenheit scale? A) 5 0 F B) 0 0 F C) -5 0 F D) F E) F 9. A pair of eyeglass frames is made of epoxy plastic. At 20 0 C, the frames have circular lens holes 3.12 cm in radius. To what temperature must the fames be heated or cooled in order to insert lenses 3.13 cm in radius? (α epoxy = 1.6x10-4 / 0 C). A) 5 0 C B) 10 0 C C) 20 0 C D) 40 0 C E) 50 0 C 10. When a bimetallic strip is heated, the strip will bend toward the side A) with larger coefficient of linear expansion. B) with the smaller coefficient of linear expansion. C) with the higher temperature. D) with the lower temperature. E) can t tell. 11. The volume of the iron cube, 5 cm on edge, will increase by what amount if it is heated from 20 0 C to C? (The coefficient of linear expansion of iron is 1.2 x 10-5 per 0 C ) A) cm 3 B) cm 3 C) cm 3 D) cm 3 E) cm A concrete highway is built of slabs 12 m long at How wide should the expansion cracks between the slabs be at 20 0 to prevent buckling at temperature 50 0 C? (the coefficient of linear expansion of concrete is α = 12x10-6 /C 0 ) A) 9.0 mm B) 2.0 mm C) 28.0 mm D) 4.5 mm E) can t tell 3

5 EXAM 2 PHYS 103 VERSION A SPRING 2007 Workout problem 1 ( 2 points) A water line enters a house 2 m below the ground. A smaller diameter pipe of radius of 2.3 cm carries water to a faucet 5 m above the ground, on the second floor. Water flows at 2.2 m/s in the main line of radius of 32 cm. a. Find the speed of the water in the smaller pipe. Ans. b) If the pressure in the main line is 2.65x10 5 Pa, what is the pressure in the pipe on the second floor? Ans Workout problem 2 ( 2 points) Steel rails for an interurban transit system form a continuous track that is held rigidly in place in concrete. a) If the track was laid when the temperature was 0 0 C, what is the stress in the rails on a warm day when the temperature is 45 0 C? Ans b) What fraction of the ultimate strength of the steel does it represent? Ans c) At what temperature could the steel rails rupture? Ans. ( E = 200x10 9 Pa, the ultimate strength = 400x10 6 Pa, α = 12x10-6 /K ) 4

EXAM 1 PHYS 103 FALL 2011 A NAME: SECTION

EXAM 1 PHYS 103 FALL 2011 A NAME: SECTION As a student at NJIT I, will conduct myself in a professional manner and will comply with the provisions of the NJIT Academic Honor Code. I also understand that