Concept explainers
Why is the following situation impossible? In a large city with an air-pollution problem, a bus has no combustion engine. It runs over its citywide route on energy drawn from a large, rapidly rotating flywheel under the floor of the bus. The flywheel is spun up to its maximum rotation rate of 3 000 rev/min by an electric motor at the bus terminal. Every time the bus speeds up, the flywheel slows down slightly. The bus is equipped with regenerative braking so that the flywheel can speed up when the bus slows down. The flywheel is a uniform solid cylinder with mass 1 200 kg and radius 0.500 m. The bus body does work against air resistance and rolling resistance at the average rate of 25.0 hp as it travels its route with an average speed of 35.0 km/h.
Trending nowThis is a popular solution!
Chapter 10 Solutions
PHYSICS:F/SCI.+ENGRS.(LL)-W/WEBASSIGN
- Why is the following situation impossible? A space station shaped like a giant wheel has a radius of r = 100 m and a moment of inertia of 5.00 108 kg m2. A crew of 150 people of average mass 65.0 kg is living on the rim, and the stations rotation causes the crew to experience an apparent free-fall acceleration of g (Fig. P10.52). A research technician is assigned to perform an experiment in which a ball is dropped at the rim of the station every 15 minutes and the time interval for the ball to drop a given distance is measured as a test to make sure the apparent value of g is correctly maintained. One evening, 100 average people move to the center of the station for a union meeting. The research technician, who has already been performing his experiment for an hour before the meeting, is disappointed that he cannot attend the meeting, and his mood sours even further by his boring experiment in which every time interval for the dropped ball is identical for the entire evening.arrow_forwardLara is running just outside the circumference of a carousel, looking for her favorite horse to ride, with a constant angular speed of 1.00 rad/s. Just as she spots the horse, one-fourth of the circumference ahead of her, the carousel begins to move, accelerating from rest at 0.050 rad/s2. a. Taking the time when the carousel begins to move as t = 0, when will Lara catch up to the horse? b. Lara mistakenly passes the horse and keeps running at constant angular speed. If the carousel continues to accelerate at the same rate, when will the horse draw even with Lara again?arrow_forwardA disk with moment of inertia I1 rotates about a frictionless, vertical axle with angular speed i. A second disk, this one having moment of inertia I2 and initially not rotating, drops onto the first disk (Fig. P10.50). Because of friction between the surfaces, the two eventually reach the same angular speed f. (a) Calculate f. (b) Calculate the ratio of the final to the initial rotational energy. Figure P10.50arrow_forward
- Why is the following situation impossible? In a large city with an air-pollution problem, a bus has no combustion engine. It runs over its citywide route on energy drawn from a large, rapidly rotating flywheel under the floor of the bus. The flywheel is spun up to its maximum rotation rate of 3 000 rev/min by an electric motor at the bus terminal. Every time the bus speeds up, the flywheel slows down slightly. The bus is equipped with regenerative braking so that the flywheel can speed up when the bus slows down. The flywheel is a uniform solid cylinder with mass 1 200 kg and radius 0.500 m. The bus body does work against air resistance and rolling resistance at the average rate of 25.0 hp as it travels its route with an average speed of 35.0 km/h.arrow_forwardFnet = ma, Ffric,k = MkN, Ffric,s,max = μs N₁ v=rw, ac v2 = ²/² = rw², Fnet,c = mac rarrow_forwardA lawnmower engine brings a 1 m-long by 0.1 m-wide cutting blade of mass 2.55 kg from rest to an angular speed of 1800 rpm in 1.27 seconds. What is the average power supplied by the engine during this period? 2910 W 2940 W 2970 W 3000 W 3030 Warrow_forward
- The Gravitron is an amusement ride that spin riders around in a circle. Riders are located around the edge (R = 5m from the axis) and it takes 14 seconds for them to reach a speed of 7 m/s. The riders get precisely one minute of fun at this speed before a friction brake is applied to the Gravitron's 0.25m diameter axle. The Gravitron makes four complete revolutions while stopping. The Gravitron itself has a moment of inertia of I to 45 people at a time. %3D 1.44 x 105kgm² and can hold up a. What is the total duration of the ride? Show your work. b. Assuming that the ride is at full capacity and the average mass of a person is 62kg, what is the total inertia of the system? Show your work. c. What is the frictional force applied by the break? Show your work.arrow_forwardThe wheel in the figure has eight equally spaced spokes and a radius of 50 cm. It is mounted on a fixed axle and is spinning at 3.7 rev/s. You want to shoot a 23-cm-long arrow parallel to this axle and through the wheel without hitting any of the spokes. Assume that the arrow and the spokes are very thin. What minimum speed must the arrow have? Number Units Use correct number of significant digits; the tolerance is +/-2%arrow_forwardConsider a basketball player spinning a ball on the tip of a finger. If such a player performs 1.93 J of work to set the ball spinning from rest, at what angular speed will the ball rotate? Model a basketball as a thin‑walled, hollow sphere. For men's basketball, the ball has a circumference of 74.9 cm and a mass of 624 g.arrow_forward
- Physics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningPhysics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning