Concept explainers
* Stopping Earth’s rotation Suppose that Superman wants to stop Earth so it does not rotate. He exerts a force on Earth
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Chapter 9 Solutions
College Physics: Explore And Apply, Volume 2 (2nd Edition)
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Physics for Scientists and Engineers with Modern Physics
The Cosmic Perspective (8th Edition)
Essential University Physics: Volume 2 (3rd Edition)
Modern Physics
Cosmic Perspective Fundamentals
- The motion of spinning a hula hoop around one's hips can bemodeled as a hoop rotating around an axis not through the center, but offset from the center by an amount h, where h is lessthan R, the radius of the hoop. Suppose Maria spins a hula hoopwith a mass of 0.75 kg and a radius of 0.62 m around her waist.The rotation axis is perpendicular to the plane of the hoop, butapproximately 0.40 m from the center of the hoop. a. What isthe rotational inertia of the hoop in this case? b. If the hula hoopis rotating with an angular speed of 13.7 rad/s, what is its rotational kinetic energy?arrow_forwardA bicyclist is testing a new racing bike on a circular track ofradius 53.0 m. The bicyclist is able to maintain a constant speedof 24.0 m/s throughout the test run. a. What is the angularspeed of the bike? b. What are the magnitude and direction ofthe bikes acceleration?arrow_forward(a) What is the angular momentum of the Moon in its orbit around Earth? (b) How does this angular momentum compare with the angular momentum of the Moon on its axis? Remember that the Moon keeps one side toward Earth at all times. (c) Discuss whether the values found in parts (a) and (b) seem consistent with the fact that tidal effects with Earth have caused the Moon to rotate with one side always facing Earth.arrow_forward
- Saturns ring system forms a relatively thin, circular disk in the equatorial plane of the planet. The inner radius of the ring system is approximately 92,000 km from the center of the planet, and the outer edge is about 137,000 km from the center of the planet. The mass of Saturn itself is 5.68 1026 kg. a. What is the period of a particle in the outer edge compared with the period of a particle in the inner edge? b. How long does it take a particle in the inner edge to move once around Saturn? c. While this inner-edge particle is completing one orbit abound Saturn, how far around Saturn does a particle on the outer edge move?arrow_forward(a) What is the period of rotation of Earth in seconds? (b) What is the angular velocity of Earth? (c) Given that Earth has a radius of 6.4106 m at its equator, what is the linear velocity at Earth's surface?arrow_forwardHarry Potter decides to take Pottery 101 as an elective to satisfy his arts requirement at Hog warts. He sets some clay (m = 3.25 kg) on the edge of a pottery wheel (r = 0.600 m), which is initially motionless. He then begins to rotate the wheel with a uniform acceleration, reaching a final angular speed of 2.400 rev/s in 3.00 s. a. What is the speed of the clay when the initial 3.00 s has passed? b. What is the centripetal acceleration of the clay initially and when the initial 3.00 s has passed? c. What is the magnitude of the constant tangential acceleration responsible for starting the clay in circular motion?arrow_forward
- A pulsar is a rapidly rotating neutron star. The Crab nebula pulsar in the constellation Taurus has a period of 33.510-3s , radius 10.0 km, and mass 2.81030kg . The pulsar’s rotational period will increase over time due to the release of electromagnetic radiation, which doesn’t change its radius but reduces its rotational energy. (a) What is the angular momentum of the pulsar? (b) Suppose the angular velocity decreases at a rate of 1014rad/s2 . What is the torque on the pulsar?arrow_forwardHarry sets some clay (m = 3.25 kg) on the edge of a pottery wheel (r = 0.600 m), which is initially motionless. He then begins to rotate the wheel with a uniform acceleration, reaching a final angular speed of 2.400 rev/s in 3.00 s, while not touching the clay. As a result, the clay is subject to a tangential and centripetal acceleration while it sits on the edge of the wheel. a. What force is responsible for the tangential acceleration, and what force is responsible for the centripetal acceleration? b. Which of these two forces, tangential or centripetal, will necessarily fail to keep the clay in place on the wheel first? Why?arrow_forwardSuppose when Earth was created, it was not rotating. However, after the application of a uniform torque after 6 days, it was rotating at 1 rev/day. (a) What was the angular acceleration during the 6 days? (b) What torque was applied to Earth during this period? (c) What force tangent to Earth at its equator would produce this torque?arrow_forward
- Artificial gravity is produced in a space station by rotating it, so it is a noninertial reference frame. The rotation means that there must be a centripetal force exerted on the occupants: this centripetal force is exerted by the walls of the station. The space station in Arthur C. Clarkes 2001: A Space Odyssey is in the shape of a four-spoked wheel with a diameter of 155 m. If the space station rotates at a rate of 2.40 revolutions per minute, what is the magnitude of the artificial gravitational acceleration provided to a space tourist walking on the inner wall of the station?arrow_forwardA particle of mass m moves along a straight line with constant velocity v0 in the x direction, a distance b from the x axis (Fig. P13.10). (a) Does the particle possess any angular momentum about the origin? (b) Explain why the amount of its angular momentum should change or should stay constant. (c) Show that Keplers second law is satisfied by showing that the two shaded triangles in the figure have the same area when . Figure P13.10arrow_forwardModel the Moons orbit around the Earth as an ellipse with the Earth at one focus. The Moons farthest distance (apogee) from the center of the Earth is rA = 4.05 108 m, and its closest distance (perigee) is rP = 3.63 108 m. a. Calculate the semimajor axis of the Moons orbit. b. How far is the Earth from the center of the Moons elliptical orbit? c. Use a scale such as 1 cm 108 m to sketch the EarthMoon system at apogee and at perigee and the Moons orbit. (The semiminor axis of the Moons orbit is roughly b = 3.84 108 m.)arrow_forward
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningUniversity Physics Volume 1PhysicsISBN:9781938168277Author:William Moebs, Samuel J. Ling, Jeff SannyPublisher:OpenStax - Rice UniversityCollege PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax College
- Glencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-HillPhysics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
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