Concept explainers
A damaged 1200-kg car is being towed by a truck. Neglecting the friction, air drag, and rolling resistance, determine the extra power required (a) for constant velocity on a level road, (b) for constant velocity of 50 km/h on a 30° (from horizontal) uphill road, and (c) to accelerate on a level road from stop to 90 km/h in 12 s.
(a)
The extra power required for constant velocity on a level road.
Answer to Problem 34P
The extra power required for constant velocity on a level road is
Explanation of Solution
Write the equation of total power required during the rates of changes in potential and kinetic energies.
Here, the power needed to acceleate the body is
Conclusion:
Since the velocity is constant on a level road, the extra power required will be considered as zero.
Thus, the extra power required for constant velocity on a level road is
(b)
The extra power required for constant velocity of 50 km/h on a
Answer to Problem 34P
The extra power required for constant velocity of 50 km/h on a
Explanation of Solution
Calculate the value of
Here, mass of a damaged car is m, acceleration due to gravity is g, difference between the elevation of ski lift is
Conclusion:
Since the velocity is constant on a level road, the extra power needed to acceleate the body is considered as zero.
Substitute 1200 kg for m,
Substitute 0 for
Thus, the extra power required for constant velocity of 50 km/h on a
(c)
The extra power required to accelerate on a level road from stop to 90 km/h in 12 s.
Answer to Problem 34P
The extra power required to accelerate on a level road from stop to 90 km/h in 12 s is
Explanation of Solution
Calculate the value of
Here, initial and final velocity of a car is
Conclusion:
Since the car is accelerated on a level road, the value of
Substitute 1200 kg for m, 12 s for
Substitute 0 for
Thus, the extra power required to accelerate on a level road from stop to 90 km/h in 12 s is
Want to see more full solutions like this?
Chapter 2 Solutions
THERMODYNAMICS: ENG APPROACH LOOSELEAF
Additional Engineering Textbook Solutions
Fluid Mechanics: Fundamentals and Applications
Statics and Mechanics of Materials (5th Edition)
Engineering Mechanics: Statics
Machine Tool Practices (10th Edition)
Shigley's Mechanical Engineering Design (McGraw-Hill Series in Mechanical Engineering)
Applied Statics and Strength of Materials (6th Edition)
- A ski lift has a one-way length of 1 km and a vertical rise of 200 m. The chairs are spaced 20 m apart, and each chair can seat three people. The lift is operating at a steady speed of 10 km/h. Neglecting friction and air drag, and assuming that the average mass of each loaded chair is 250 kg, determine the power required to operate this ski lift. Also, estimate the power required to accelerate this ski lift in 9 s to its operating speed when it is first turned on. The power required to operate the ski lift is 68.125 Numeric ResponseEdit Unavailable. 68.125 correct.kW. The power required to accelerate this ski life in 9 s to its operating speed is 38.84 Numeric ResponseEdit Unavailable. 38.84 correct.kW.arrow_forwardA ski lift has a one-way length of 1 km and a vertical rise of 200 m. The chairs are spaced 20 m apart, and each chair can seat three people. The lift is operating at a steady speed of 10 km/h. Neglecting friction and air drag, and assuming that the average mass of each loaded chair is 250 kg, determine the power required to operate this ski lift. Also, estimate the power required to accelerate this ski lift in 9 s to its operating speed when it is first turned on. The power required to operate the ski lift is kW. The power required to accelerate this ski life in 9 s to its operating speed is kW. Nextarrow_forwardA loaded truck weighs 16(10^3)lb and accelerates uniformly on a level road from 15 ft/s to 30 ft/s during 4 s. If the frictional resistance to motion is 325 lb, determine the maximum power that must be delivered to the wheelsarrow_forward
- A 40.0-kg box initially at rest is pushed 5.00 m along a rough, horizontal floor with a constant applied horizontal force of 130 N. If the coefficient of friction between box and floor is 0.300, find (a) the work done by the applied force, (b) the increase in internal energy in the box-floor system due to friction,arrow_forwardHow can you define impulsive force in terms of momentum.arrow_forwardA physics professor is pushed up a ramp inclined upward at 30.0° above the horizontal as she sits in her desk chair, which slides on frictionless rollers. The combined mass of the professor and chair is 85.0 kg. She is pushed 2.50 m along the incline by a group of students who together exert a constant horizontal force of 600 N. The professor’s speed at the bottom of the ramp is 2.00 m/s. Use the work–energy theorem to find her speed at the top of the ramp.arrow_forward
- A 60-kg person is carrying a 3-kg box walking (1) a ramp at a constant speed of 0.5 m/s. The ramp has 35° angle and 50m slope length. At the same time, 25 kJ of heat is being transferred (2) the box and 10 kJ/kg (3) of internal energy took place inside the box. Determine the work done by/to the box. Clearly indicate your system and assumptions for full mark. (1) (2) (3) down to increasearrow_forwardA truck hauls a trailer at 60 km/hour when exerting a steady pull of 600 N. If the work is done for 40 minutes, the power required isarrow_forwardA 200 g block is pressed against a spring of force constant 1.4 kN/m until it is compressed by 10 cm. The spring rests on a horizontal plane. Determine how much the block moves before stopping if the coefficient of friction is 0.3.arrow_forward
- An automobile produces 20 kW when moving with a velocity of 50 km/hr. Determine (a) the resisting force.arrow_forwardA 7.0-kg block on a horizontal frictionless surface is attached to a light spring (force constant - 1.2 kN/m). The block is initially at rest at its equilibrium position when a force of magnitude P acting parallel to the surface is applied to the block, as shown. When the block is 8.0 cm from the equilibrium position, it has a speed of 0.80 m/s. How much work is done on the block by the force P as the block moves the 8.0 cm? xxxxxxxxarrow_forward1. A skier of mass 42.1 kg starts at the top of a hill with a speed of 5.30 m/s. The hill is angled at 27.20 and is 11.2 m high. The skis have jets that do 575 J of work. The coefficient of kinetic friction between the skis and the snow is 0.100. When the skier gets to the bottom of the hill, the skier slides on horizontal ground that is frictionless. A spring with a spring constant of 145 N/m is 1.0 m from the bottom of the hill to stop the skier. A) How fast is skier moving at the bottom of the hill? B) How far is the spring compressed to stop the skier? Pictorial Representation Mathematical Representation Aa MacBook Pro DII DD 吕0 G00 000 FB F9 F10 F4 F5 F6 F7 F3 * #3 2$ 4 7 8. E R A LOarrow_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