Mechanical Engineering

The rigid gate, OAB, of Fig. P11.23 is hinged at O and rests against a rigid support at B. What minimum horizontal force, P, is required to hold the gate closed if its width is 3 m? Neglect the weight of the gate and friction in the hinge. The back of the gate is exposed to the atmosphere.

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The rigid gate, OAB, of Fig. P11.23 is hinged at O and rests against a rigid support at B. What minimum horizontal force, P, is required to hold the gate closed if its width is 3 m? Neglect the weight of the gate and friction in the hinge. The back of the gate is exposed …

The rigid gate, OAB, of Fig. P11.23 is hinged at O and rests against a rigid support at B. What minimum horizontal force, P, is required to hold the gate closed if its width is 3 m? Neglect the weight of the gate and friction in the hinge. The back of the gate is exposed to the atmosphere. Read More »

For a fiber-reinforced composite, the efficiency of reinforcement η is dependent on fiber length L according to:

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For a fiber-reinforced composite, the efficiency of reinforcement η is dependent on fiber length L according to: η = (L – 2x)/L where x represents the length of the fiber at each end that does not contribute to the load transfer. a) Using MATLAB, plot η versus L (up to L = 40 mm) assuming …

For a fiber-reinforced composite, the efficiency of reinforcement η is dependent on fiber length L according to: Read More »

Crude oil flows through a level section of the Alaskan pipeline at a rate of 1.6 million barrels per day (1 barrels=42 US gallons) the pipe inside diameter is 48 inch and its roughness is equivalent to galvanized iron. The maximum allowable pressure is 1200 psi. At the pumping temperature of 140F, the crude oil has S.G 0.93 and a viscosity of 16.75cP, and a vapour pressure of 50 psi. a)for these conditions, determine the maximum possible spacing between pumping stations(i.e the pipeline will consist of repeating pump-pipe sections to meet the above mentioned criteria) b) Next, if the pump efficiency is 85%, determine the power that must be supplied to the pump at each pumping station( assume pump friction is negligible)

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Crude oil flows through a level section of the Alaskan pipeline at a rate of 1.6 million barrels per day (1 barrels=42 US gallons) the pipe inside diameter is 48 inch and its roughness is equivalent to galvanized iron. The maximum allowable pressure is 1200 psi. At the pumping temperature of 140F, the crude oil …

Crude oil flows through a level section of the Alaskan pipeline at a rate of 1.6 million barrels per day (1 barrels=42 US gallons) the pipe inside diameter is 48 inch and its roughness is equivalent to galvanized iron. The maximum allowable pressure is 1200 psi. At the pumping temperature of 140F, the crude oil has S.G 0.93 and a viscosity of 16.75cP, and a vapour pressure of 50 psi. a)for these conditions, determine the maximum possible spacing between pumping stations(i.e the pipeline will consist of repeating pump-pipe sections to meet the above mentioned criteria) b) Next, if the pump efficiency is 85%, determine the power that must be supplied to the pump at each pumping station( assume pump friction is negligible) Read More »

The figure shows a rectangular loop of wire of 80 turns, 13.0by 28.0 cm. It carries a curent of 2.04 A and is hinged at oneside. What is the magnitude of the torque that acts on the loop, ifit is mounted with its plane at an angle of 46.0 degrees to thedirection of B, which is uniform and equal to0.50 T?

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The figure shows a rectangular loop of wire of 80 turns, 13.0by 28.0 cm. It carries a curent of 2.04 A and is hinged at oneside. What is the magnitude of the torque that acts on the loop, ifit is mounted with its plane at an angle of 46.0 degrees to thedirection of B, which is …

The figure shows a rectangular loop of wire of 80 turns, 13.0by 28.0 cm. It carries a curent of 2.04 A and is hinged at oneside. What is the magnitude of the torque that acts on the loop, ifit is mounted with its plane at an angle of 46.0 degrees to thedirection of B, which is uniform and equal to0.50 T? Read More »

1-8 Discussions Discuss or explain each of the followings: 1. Effect of the carbon percentage on the shape and magnitude (mechanical properties) of stress-strain curve. 2. Effect of the material heat treatment on the shape and magnitude of the stress-strain curve. 3. Differentiate between the behaviors of metallic and non-metallic materials under tensile test. 4. Affect of prior history of plastic deformation on the shape and magnitude of the stress-strain curve. 5. Effect of the strain rate and temperature on the shape and magnitude of the stress- strain curve. 6. Effect of the material grain size on the shape and magnitude of the stress-strain curve.

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EXPERT ANSWER 1. Effect of carbon percentage Based on carbon percentage, material is classified broadly into steels and cast iron. Generally, Cast Iron has a carbon percentage of above 2.11% while less than that is considered as steels. Higher carbon percentage means more brittle material and hence less ductile material. Hence, for lower carbon material …

1-8 Discussions Discuss or explain each of the followings: 1. Effect of the carbon percentage on the shape and magnitude (mechanical properties) of stress-strain curve. 2. Effect of the material heat treatment on the shape and magnitude of the stress-strain curve. 3. Differentiate between the behaviors of metallic and non-metallic materials under tensile test. 4. Affect of prior history of plastic deformation on the shape and magnitude of the stress-strain curve. 5. Effect of the strain rate and temperature on the shape and magnitude of the stress- strain curve. 6. Effect of the material grain size on the shape and magnitude of the stress-strain curve. Read More »

1. Consider an acrobatic aircraft pilot making a perfect circular looping in the air. At the highest point of the looping the altitude is recorded as 3,500 ft and at the lowest point of the looping, the altitude is given as 2,800 ft. • What is the tum radius in the circular looping motion? • Compare the load factor at the highest and the lowest points of the circular looping. Which one corresponds to the lowest load factor? Assume that the looping is made such that the lowest load factor (1.e. the lower load factor in (b)) is zero. What is the instantaneous tum rate at this point? 2. A propeller-driven aircraft is flying with energy height of 20,000 ft at its service ceiling altitude. It is flying at its minimum thrust required conditions and its velocity at this moment is 400 ft/s. The pilot then changes the aircraft’s velocity in order to make a steady climbing manoeuvre to reach higher cruising altitude at the fastest rate possible. Solve for the new energy height of the aircraft after climbing for 3 minutes, assuming the effect of altitude on the rate of climb is negligible during this short climb. 3. A jet aircraft has the following characteristics: takeoff gross weight = 60,000 lb, wing area = 950 ft”, thrust during takeoff=17,000 lb, lift coefficient for ground roll = 0.1 and drag polar, Cp = 0.02 +0.035 C++. The aircraft is to take off from an airport with the following conditions: free stream air density is 2.3769 x 10-3 slugs/ft? gravitational acceleration = 32.2 ft/s and based on the runway surface, the coefficient of ground rolling friction can be taken as 0.05 (with brakes off) and 0.5 (with brakes on). The lift- off velocity of the aircraft is 120 ft/s and time between initiation of rotation and lift-off = 3 seconds. Analyze the required maximum lift coefficient for the aircraft to take-off from this airport, if the allowable ground roll is only 2.500 ft. Hint: Do not make any assumption for the lift-off velocity and for ground roll calculation, use the following formula: 1.21(W/S)) 2W S +1.11 I D Vp. SC. -14, W W Jo.7V,

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A gas-turbine power plant has a two-stage compressor and a two-stage turbine. The compressors and turbines are mounted on the same shaft. The pressure and temperature at the inlet of the low-pressure compressor are 1.5 bar and 20 degree C. The maximum cycle temperature and pressure are 750 degree C and 6 bar. An intercooler, a reheater, and a regenerator are used in the cycle as shown in the figure below. Gases exiting the low-pressure compressor are cooled to the 20 degree C in the intercooler, at a pressure of 3 bar, before entering the high-pressure compressor. Gases exiting the high-pressure compressor are initially heated in a regenerator, using the gases exiting the low-pressure turbine as shown in the figure below, and later in a combustion chamber. Gases exiting the high-pressure turbine are heated to 750 degree C in the reheater, at a pressure of 3 bar, before entering the low-pressure turbine. Assume the isentropic efficiencies of the compressors and turbines to be 82%. There are no pressure losses in the intercooler, regenerator, combustion chamber and reheater. The working fluid used in the cycle is air and for air, take k = 1.4 and c_p = 1.004 kJ/kg. Also, use T(K) = T(degree C) + 273 and 1 bar = 10^5 Pa. Determine T-s diagram of the cycle; Thermal efficiency of the cycle when the regenerator effectiveness is 0.7; and The mass flow rate if the net power generated is 350 kW.

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2 A composite material consists of parallel fibers of Young’s modulus E in a matrix of Young’s modulus Em. The volume fraction of fibers is V. Derive an expression for E. Young’s modulus of the composite along the direction of the fibers, in terms of E, Em and V. Obtain an analogous expression for the density of the composite, pe Using material parameters given in the next table, find pe and E for the following composites: (a) carbon fiber-epoxy resin (V= 0.5), (b) glass fiber-polyester resin (V: = 0.5), (c) steel-concrete (V: = 0.02). Young’s modulus (GN m2 390 Density (Mg m) 1.90 2.55 1.15 Material Carbon fiber Glass fiber Epoxy resin Polyester resin Steel Concrete 72 3 } 7.90 2.40 200 45

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2. a. Water initially at 10°C and mass flow rate 0.001 kg/s (3.6 kg/hr) enters a tube D 2 mm of high thermal conductivity and negligible wall thickness. If the tube is subjected to boiling water T-100°C on its outside surface, calculate the required length of tube if the water is to be at 90°C at the outlet of the tube assuming that the tube is long enough that the effect of the entrance length may be neglected. Estimate the entrance length. 90c boiling water at 100 C water 3.6 kg/hr 10°C b. If the flowrate were increased x10 (to 36 kg/hr) and the length of the pipe was set to be 0.5 m (not the answer to part al, what will be the outlet temperature of the water?

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