Concept explainers
The drag coefficient of a vehicle increases when its windows are rolled down or its sunroof is opened. A sports car has a frontal area of 18 ft2 and a drag coefficient of 0.32 when the windows and sunroof are closed. The drag coefficient increases to 0.41 when the sunroof is open. Determine the additional power consumption of the car when the sunroof is opened at (a) 35 mi/h and (b) 70 mi/h. Take the density of be to be 0.075 Ibm/ft3.
(a)
The additional power consumption of the car when the roof opened at
Answer to Problem 41EP
Explanation of Solution
Given information:
Concept used:
Calculation:
Conclusion:
The additional power consumption of the car when the roof opened at
(b)
The additional power consumption of the car when the roof opened at
Answer to Problem 41EP
Explanation of Solution
Given information:
Concept used:
Calculation:
Conclusion:
The additional power consumption of the car when the roof opened at
Want to see more full solutions like this?
Chapter 11 Solutions
Connect Access for Fluid Mechanics
- The drag coefficient of a vehicle increases when its windows are rolled down or its sunroof is opened. A sports car has a frontal area of 18 ft2 and a drag coefficient of 0.32 when the windows and sunroof are closed. The drag coefficient increases to 0.41 when the sunroof is open. Determine the additional power consumption of the car when the sunroof is opened at (a) 35 mi/h and (b) 70 mi/h. Take the density of air to be 0.075 lbm/ft3.arrow_forwardThe drag coefficient of a vehicle increases when its windows are rolled down or its sunroof is opened. A sports car has a frontal area of 18 ft2 and a drag coefficient of 0.32 when the windows and sunroof are closed. The drag coefficient increases to 0.41 when the sunroof is open. Take the density of air to be 0.075 lbm/ft3. Determine the additional power consumption of the car when the sunroof is opened at (a) 32 mi/h and (b) 70 mi/h.arrow_forwardA 17,000-kg tractor-trailer rig has a frontal area of 9.2 m2, a drag coefficient of 0.96, a rolling resistance coefficient of 0.05 (multiplying the weight of a vehicle by the rolling resistance coefficient gives the rolling resistance), a bearing friction resistance of 350 N, and a maximum speed of 110 km/h on a level road during steady cruising in calm weather with an air density of 1.25 kg/m3. Now a fairing is installed to the front of the rig to suppress separation and to streamline the flow to the top surface, and the drag coefficient is reduced to 0.76. Determine the maximum speed of the rig with the fairing.arrow_forward
- The drag coefficient of a car at the design conditions of 1 atm, 70°F, and 60 mi/h is to be determined experimentally in a large wind tunnel in a full-scale test. The frontal area of the car is 22.26 ft2. If the force acting on the car in the flow direction is measured to be 68 lbf, determine the drag coefficient of this car.arrow_forwardA commercial airplane has a total mass of 150,000 lbm and a wing planform area of 1700 ft2. The plane has a cruising speed of 625 mi/h and a cruising altitude of 38,000 ft where the air density is 0.0208 lbm/ft3. The plane has double-slotted flaps for use during takeoff and landing, but it cruises with all flaps retracted. Assuming the lift and drag characteristics of the wings can be approximated by NACA 23012, determine (a) the minimum safe speed for takeoff and landing with and without extending the flaps, (b) the angle of attack to cruise steadily at the cruising altitude, and (c) the power that needs to be supplied to provide enough thrust to overcome drag. Take the air density on the ground to be 0.075 lbm/ft3.arrow_forwardA commercial airplane has a total mass of 70,000 kg and a wing planform area of 150 m2. The plane has a cruising speed of 558 km/h and a cruising altitude of 12,000 m, where the air density is 0.312 kg/m3. The plane has double-slotted flaps for use during takeoff and landing, but it cruises with all flaps retracted. Assuming the lift and the drag characteristics of the wings can be approximated by NACA 23012 , determine (a) the minimum safe speed for takeoff and landing with and without extending the flaps, (b) the angle of attack to cruise steadily at the cruising altitude, and (c) the power that needs to be supplied to provide enough thrust to overcome wing drag.arrow_forward
- , A small aircraft has a wing area of 40 m2a lift coefficient of 0.45 at takeoff settings, and a total mass of 4000 kg. Determine (a) the takeoff speed of this aircraft at sea level at standard atmospheric conditions, (b) the wing loading, and (c) the required power to maintain a constant cruising speed of 360 km/h for a cruising drag coefficient of 0.035.arrow_forwardHow does a winglet on the wing tip reduce induced drag? Which drag is higher if an aircraft is flying at 100knts and the L/Dmax is 120knts? How do you know this?arrow_forwardDefine the planform area of a body subjected to external flow. When is it appropriate to use the planform area in drag and lift calculations?arrow_forward
- The power delivered to the wheels of a car is used to overcome aerodynamic drag. Compare the amount of annual fuel consumption by the car when driving a distance of 24,000 km/year with velocities of 60, 100 and 140 km/h. The drag coefficient and frontal area of the car body are 0.26 and 1.8 m2 and the engine efficiency is 30%. Take the density of air and gasoline as 1.2 and 750 kg/m3. The heating value of gasoline is also 44,000 kJ/kg.arrow_forwardWhat effect does increasing the Reynolds number have on coefficient of lift and drag?arrow_forwardNellie and Goldie are coasting on their bicycles down a 10° slope at 15 m/s through still air. The mass of Nellie and her bicycle is 60 kg. The mass of Goldie and her bicycle is 90 kg. The cross-sectional area of Nellie and her bicycle is 0.45, while the cross-sectional area of Goldie and her bicycle is 0.60. The drag coefficient for both cyclists is 0.70. Other than gravity and air resistance, the external forces acting on the two bicycle and rider systems are the same. Which cyclist is more affected by air resistance, and why?arrow_forward
- Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University PressMechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSONThermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
- Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEYMechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage LearningEngineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY