Fundamentals of Thermal-Fluid Sciences
5th Edition
ISBN: 9780078027680
Author: Yunus A. Cengel Dr., Robert H. Turner, John M. Cimbala
Publisher: McGraw-Hill Education
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Chapter 3, Problem 76RQ
To determine
The heating system with the lowest energy cost.
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Q3:
(10 MARKS)
A piston with a weight of 29.4 N is supported by a spring
and dashpot. A dashpot of damping coefficient c = 275
N.s/m acts in parallel with the spring of stiffness k = 2400
N/m. A fluctuating pressure p = 960 sin 30t N/m² acts on
the piston, whose top surface area is 0.05 m². Determine
the steady-state displacement as a function of time and the
maximum force transmitted to the base.
P=Po sin cot
W
9. Design a spur gear drive required to transmit 45 kW at a pinion speed of 800 r.p.m. The velocity ratio
is 3.5 : 1. The teeth are 20° full-depth involute with 18 teeth on the pinion. Both the pinion and gear
are made of steel with a maximum safe static stress of 180 MPa. Assume a safe stress of 40 MPa for
the material of the shaft and key.
10. Design a pair of spur gears with stub teeth to transmit 55 kW from a 175 mm pinion running at 2500
r.p.m. to a gear running at 1500 r.p.m. Both the gears are made of steel having B.H.N. 260. Approximate
the pitch by means of Lewis equation and then adjust the dimensions to keep within the limits set by
the dynamic load and wear equation.
7. A motor shaft rotating at 1440 r.p.m. has to transmit 15 kW to a low speed shaft rotating at 500 r.p.m.
The teeth are 20° involute with 25 teeth on the pinion. Both the pinion and gear are made of cast iron
with a maximum safe stress of 56 MPa. A safe stress of 35 MPa may be taken for the shaft on which
the gear is mounted. Design and sketch the spur gear drive to suit the above conditions. The starting
torque may be assumed as 1,25 times the running torque.
Ruins 20 LW at 100 nm to another shaft running approxi
Chapter 3 Solutions
Fundamentals of Thermal-Fluid Sciences
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Ch. 3 - Electric power is to be generated by installing a...Ch. 3 - Prob. 12PCh. 3 - Prob. 13PCh. 3 - Prob. 14PCh. 3 - A river flowing steadily at a rate of 175 m3/s is...Ch. 3 - Consider a river flowing toward a lake at an...Ch. 3 - Prob. 17PCh. 3 - Prob. 18PCh. 3 - A gas in a piston-cylinder device is compressed,...Ch. 3 - A room is heated by an iron that is left plugged...Ch. 3 - A room is heated as a result of solar radiation...Ch. 3 - An insulated room is heated by burning candles. Is...Ch. 3 - Prob. 23PCh. 3 - A model aircraft internal-combustion engine...Ch. 3 - Lifting a weight to a height of 20 m takes 20 s...Ch. 3 - A construction crane lifts a prestressed concrete...Ch. 3 - A man weighing 180 lbf is pushing a cart that...Ch. 3 - Prob. 28PCh. 3 - Determine the energy required to accelerate a...Ch. 3 - Prob. 30PCh. 3 - Prob. 31PCh. 3 - Determine the work required to deflect a linear...Ch. 3 - Prob. 33PCh. 3 - Prob. 34PCh. 3 - Prob. 35PCh. 3 - What are the different mechanisms for transferring...Ch. 3 - Prob. 37PCh. 3 - Water is being heated in a closed pan on top of a...Ch. 3 - A vertical piston-cylinder device contains water...Ch. 3 - Prob. 40PCh. 3 - A water pump increases the water pressure from 15...Ch. 3 - Prob. 42PCh. 3 - A classroom that normally contains 40 people is to...Ch. 3 - Prob. 44PCh. 3 - Consider a room that is initially at the outdoor...Ch. 3 - Prob. 46PCh. 3 - The 60-W fan of a central heating system is to...Ch. 3 - The driving force for fluid flow is the pressure...Ch. 3 - Prob. 49PCh. 3 - Prob. 50PCh. 3 - How is the combined pump–motor efficiency of a...Ch. 3 - Define turbine efficiency, generator efficiency,...Ch. 3 - Prob. 53PCh. 3 - Consider a 24-kW hooded electric open burner in an...Ch. 3 - Prob. 55PCh. 3 - Prob. 56PCh. 3 - The steam requirements of a manufacturing facility...Ch. 3 - Prob. 59PCh. 3 - Prob. 60PCh. 3 - Prob. 61PCh. 3 - The water in a large lake is to be used to...Ch. 3 - Prob. 63PCh. 3 - Prob. 64PCh. 3 - Reconsider Prob. 3–64. Using an appropriate...Ch. 3 - Prob. 66PCh. 3 - Prob. 67PCh. 3 - Prob. 68PCh. 3 - Prob. 69PCh. 3 - Prob. 70PCh. 3 - Prob. 71PCh. 3 - Prob. 72PCh. 3 - Prob. 73RQCh. 3 - Prob. 74RQCh. 3 - Prob. 75RQCh. 3 - Prob. 76RQCh. 3 - Prob. 77RQCh. 3 - Prob. 78RQCh. 3 - Prob. 79RQCh. 3 - A man weighing 180 lbf pushes a block weighing 100...Ch. 3 - Prob. 81RQCh. 3 - Prob. 82RQCh. 3 - Prob. 83RQCh. 3 - Windmills slow the air and cause it to fill a...Ch. 3 - In a hydroelectric power plant, 65 m3/s of water...Ch. 3 - Prob. 86RQCh. 3 - The pump of a water distribution system is powered...
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- 6. A two stage reduction drive is to be designed to transmit 2 kW; the input speed being 960 r.p.m. and overall reduction ratio being 9. The drive consists of straight tooth spur gears only, the shafts being spaced 200 mm apart, the input and output shafts being co-axial.arrow_forward2 A metal block of mass m = 10 kg is sliding along a frictionless surface with an initial speed Vo, as indicated below. The block then slides above an electromagnetic brake that applies a force FEB to the block, opposing its motion. The magnitude of the electromagnetic force varies quadratically with the distance moved along the brake (x): 10 FEB = kx², with k = 5 N m² V₁ = 8 m/s m = 10 kg FEB Frictionless surface Electromagnetic brake ⇒x Determine how far the block slides along the electromagnetic brake before stopping, in m.arrow_forwardQ1: Determine the length, angle of contact, and width of a 9.75 mm thick leather belt required to transmit 15 kW from a motor running at 900 r.p.m. The diameter of the driving pulley of the motor is 300 mm. The driven pulley runs at 300 r.p.m. and the distance between the centers of two pulleys is 3 meters. The density of the leather is 1000 kg/m³. The maximum allowable stress in the leather is 2.5 MPa. The coefficient of friction between the leather and pulley is 0.3. Assume open belt drive.arrow_forward
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