Chapter 8: 8-8P (page 198)
A bicycle with tires 68 cm in diameter travels 9.2 km. How many revolutions do the wheels make?
Short Answer
The number of revolutions made by the tire is 4309 rev.
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Chapter 8: 8-8P (page 198)
A bicycle with tires 68 cm in diameter travels 9.2 km. How many revolutions do the wheels make?
The number of revolutions made by the tire is 4309 rev.
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(II) A rotating uniform cylindrical platform of mass 220 kg and radius 5.5 m slows down from to rest in 16 s when the driving motor is disconnected. Estimate the power output of the motor (hp) required to maintain a steady speed of\({\bf{3}}{\bf{.8 }}rev/s\).
A spherical asteroid with radius\(r = 123\;{\rm{m}}\)and mass\(M = 2.25 \times {10^{10}}\;{\rm{kg}}\)rotates about an axis at four revolutions per day. A 鈥渢ug鈥 spaceship attaches itself to the asteroid鈥檚 south pole (as defined by the axis of rotation) and fires its engine, applying a force F tangentially to the asteroid鈥檚 surface as shown in Fig. 8鈥65. If\(F = 285\;{\rm{N}}\)how long will it take the tug to rotate the asteroid鈥檚 axis of rotation through an angle of 5.0掳 by this method?

A solid sphere of a 0.72 m diameter can be rotated about an axis through its center by a torque, which accelerates it uniformly from rest through a total of 160 revolutions in 15.0 s. What is the mass of the sphere?
An Atwood machineconsists of two masses,\({m_A} = {\bf{65 kg}}\) and\({m_B} = {\bf{75 kg}}\) connected by a massless inelastic cord that passes over a pulley free to rotate, Fig. 8 52. The pulley is a solid cylinder of radius\(R = {\bf{0}}{\bf{.45 m}}\) and mass 6.0 kg. (a) Determine the acceleration of each mass. (b) What % error would be made if the moment of inertia of the pulley is ignored? (Hint: The tensions\({F_{TA}}\) and\({F_{TB}}\)are not equal. We discussed the Atwood machine in Example 4鈥13, assuming I = 0 for the pulley.)

FIGURE 8-52 Problem 47.Atwood machine.
Most of our Solar System鈥檚 mass is contained in the Sun, and the planets possess almost all of the Solar System鈥檚 angular momentum. This observation plays a key role in theories attempting to explain the formation of our Solar System. Estimate the fraction of the Solar System鈥檚 total angular momentum that is possessed by planets using a simplified model which includes only the large outer planets with the most angular momentum. The central Sun (mass\(1.99 \times {10^{30}}\;{\rm{kg}}\), radius\(6.96 \times {10^8}\;{\rm{m}}\)) spins about its axis once every 25 days and the planets Jupiter, Saturn, Uranus, and Neptune move in nearly circular orbits around the Sun with orbital data given in the Table below. Ignore each planet鈥檚 spin about its own axis.
Planet | Mean Distance from Sun\(\left( { \times {{10}^6}\;{\rm{km}}} \right)\) | Orbital Period (Earth Years) | Mass \(\left( { \times {{10}^{25}}\;{\rm{kg}}} \right)\) |
Jupiter | 778 | 11.9 | 190 |
Saturn | 1427 | 29.5 | 56.8 |
Uranus | 2870 | 84.0 | 8.68 |
Neptune | 4500 | 165 | 10.2 |
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