Physics for Scientists and Engineers: Foundations and Connections
1st Edition
ISBN: 9781133939146
Author: Katz, Debora M.
Publisher: Cengage Learning
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Textbook Question
Chapter 12, Problem 55PQ
A disk with a radius of 4.5 m has a 100-N force applied to its outer edge at two different angles (Fig. P12.55). The disk has a rotational inertia of 165 kg · m2.
- a. What is the magnitude of the torque applied to the disk in case 1?
- b. What is the magnitude of the torque applied to the disk in case 2?
- c. Assuming the force on the disk is constant in each case, what is the magnitude of the
angular acceleration applied to the disk in each case? - d. Which case is a more effective way of spinning the disk? Describe which quantity you are using to determine “effectiveness” and why you chose that quantity.
FIGURE P12.55
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Chapter 12 Solutions
Physics for Scientists and Engineers: Foundations and Connections
Ch. 12.1 - Figure 12.5 shows two rotating objects. Indicate...Ch. 12.2 - Prob. 12.2CECh. 12.2 - Prob. 12.3CECh. 12.2 - Prob. 12.4CECh. 12.2 - Prob. 12.5CECh. 12.5 - For each exercise shown in Figure 12.22, how does...Ch. 12 - Often, we model the Moon as a particle in a...Ch. 12 - Suppose a satellite orbits the Earth such that it...Ch. 12 - Prob. 3PQCh. 12 - Prob. 4PQ
Ch. 12 - A ceiling fan is rotating counterclockwise with a...Ch. 12 - As seen from above the Earths North Pole, the...Ch. 12 - A rotating objects angular position is given by...Ch. 12 - A rotating objects angular position is given by...Ch. 12 - Jupiter rotates about its axis once every 9 hours...Ch. 12 - Prob. 10PQCh. 12 - Prob. 11PQCh. 12 - Prob. 12PQCh. 12 - Prob. 13PQCh. 12 - Prob. 14PQCh. 12 - Prob. 15PQCh. 12 - A disk rolls up an inclined plane as shown in...Ch. 12 - Jeff, running outside to play, pushes on a...Ch. 12 - A potters wheel rotating at 240 rev/min is...Ch. 12 - Friction in an old clock causes it to lose 1...Ch. 12 - A wheel starts from rest and in 12.65 s is...Ch. 12 - Prob. 21PQCh. 12 - Starting from rest, a wheel reaches an angular...Ch. 12 - A potters wheel is rotating with an angular...Ch. 12 - The angular speed of a wheel is given by (t) =...Ch. 12 - Prob. 25PQCh. 12 - Prob. 26PQCh. 12 - An electric food processor comes with many...Ch. 12 - Prob. 28PQCh. 12 - A bicyclist is testing a new racing bike on a...Ch. 12 - Prob. 30PQCh. 12 - A disk is initially at rest. A penny is placed on...Ch. 12 - Prob. 32PQCh. 12 - Consider again the two wind turbines in Problem...Ch. 12 - Consider again the two wind turbines in Problem...Ch. 12 - In testing an automobile tire for proper...Ch. 12 - Prob. 36PQCh. 12 - A merry-go-round at a childrens park begins at...Ch. 12 - A wheel rotating at a constant rate of 1850...Ch. 12 - Why are doorknobs placed on the edge opposite the...Ch. 12 - Prob. 40PQCh. 12 - Prob. 41PQCh. 12 - Prob. 42PQCh. 12 - A wheel of inner radius r1 = 15.0 cm and outer...Ch. 12 - A uniform plank 6.0 m long rests on two supports,...Ch. 12 - Prob. 45PQCh. 12 - Prob. 46PQCh. 12 - Prob. 47PQCh. 12 - Prob. 48PQCh. 12 - Prob. 49PQCh. 12 - Prob. 50PQCh. 12 - Prob. 51PQCh. 12 - Given a vector A=4.5+4.5j and a vector B=4.5+4.5j,...Ch. 12 - A square plate with sides 2.0 m in length can...Ch. 12 - Prob. 54PQCh. 12 - A disk with a radius of 4.5 m has a 100-N force...Ch. 12 - Disc jockeys (DJs) use a turntable in applying...Ch. 12 - Prob. 57PQCh. 12 - Prob. 58PQCh. 12 - A wheel initially rotating at 85.0 rev/min...Ch. 12 - Prob. 60PQCh. 12 - A centrifuge used for training astronauts rotating...Ch. 12 - Problems 62 and 63 are paired. 62. C A disk is...Ch. 12 - Prob. 63PQCh. 12 - A potters wheel rotates with an angular...Ch. 12 - Prob. 65PQCh. 12 - Prob. 66PQCh. 12 - Prob. 67PQCh. 12 - Lara is running just outside the circumference of...Ch. 12 - The propeller of an aircraft accelerates from rest...Ch. 12 - A ball rolls to the left along a horizontal...Ch. 12 - Three forces are exerted on the disk shown in...Ch. 12 - Consider the disk in Problem 71. The disks outer...Ch. 12 - Prob. 73PQCh. 12 - Prob. 74PQCh. 12 - Prob. 75PQCh. 12 - Prob. 76PQCh. 12 - Prob. 77PQCh. 12 - Prob. 78PQCh. 12 - Prob. 79PQCh. 12 - Prob. 80PQCh. 12 - If the rod in Problem 79 is in equilibrium, what...Ch. 12 - As a compact disc (CD) spins clockwise as seen...Ch. 12 - A disk-shaped machine part has a diameter of 40.0...Ch. 12 - Prob. 84PQ
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- A square plate with sides 2.0 m in length can rotatearound an axle passingthrough its center of mass(CM) and perpendicular toits surface (Fig. P12.53). There are four forces acting on the plate at differentpoints. The rotational inertia of the plate is 24 kg m2. Use the values given in the figure to answer the following questions. a. Whatis the net torque acting onthe plate? b. What is theangular acceleration of the plate? FIGURE P12.53 Problems 53 and 54.arrow_forwardA disk rolls up an inclined plane as shown in Figure P12.16, reaches point A, stops there momentarily, and then rolls down the inclined plane. Use the coordinate system shown to determine the direction of the angular velocity and the angular acceleration in each part of the motion as given below. If either one is zero, say so. Explain your answers. a. When the disk is going up the incline. b. At point A when the disk stops momentarily. c. When the disk is rolling down the incline FIGURE P12.16arrow_forwardA wheel of inner radius r1 = 15.0 cm and outer radius r2 = 35.0 cm shown in Figure P12.43 is free to rotate about the axle through the origin O. What is the magnitude of the net torque on the wheel due to the three forces shown? FIGURE P12.43arrow_forward
- A ball of mass M = 5.00 kg and radius r = 5.00 cm isattached to one end of a thin,cylindrical rod of length L = 15.0 cm and mass m = 0.600 kg.The ball and rod, initially at restin a vertical position and freeto rotate around the axis shownin Figure P13.70, are nudgedinto motion. a. What is therotational kinetic energy of thesystem when the ball and rodreach a horizontal position? b. What is the angular speed of the ball and rod when they reach a horizontal position? c. What is the linear speed of the centerof mass of the ball when the ball and rod reach a horizontalposition? d. What is the ratio of the speed found in part (c) tothe speed of a ball that falls freely through the same distance? FIGURE P13.70arrow_forwardThe system shown in Figure P13.18 consisting of four particles connected by massless, rigid rods is rotating around the x axis with an angular speed of 2.50 rad/s. The particle masses are m1 = 1.00 kg, m2 = 4.00 kg, m3 = 2.00 kg, and m4 = 3.00 kg. a. What is the rotational inertia of the system around the x axis? b. Using Kr=12I2 (Eq. 13.10), what is the total rotational kinetic energy of the system? c. What is the tangential speed of each of the four particles? d. Considering the system as four particles in motion and using K=i12mvi2, what is the total kinetic energy of the system? How does this value compare with the result obtained in part (b)? FIGURE P13.18arrow_forwardDisc jockeys (DJs) use a turntable in applying their trade, often using their hand to speed up or slow down a disc record so as to produce a desired change in the sound (Fig. P12.56). Suppose DJ Trick wants to slow down a record initially rotating clockwise (as viewed from above) with an angular speed of 33.0 rpm to an angular speed of 22.0 rpm. The record has a rotational inertia of 0.012 kgm2 and a radius of 0.15 m. a. What angular acceleration is necessary if he wishes to accomplish this feat in exactly 0.65 s with a constant acceleration? b. How many revolutions does the record go through during this change in speed? c. If DJ Trick applies a vertical force with his finger to the edge of the record, with what force must he push so as to slow the record in the above time? Assume the coefficient of kinetic friction between his finger and the record is 0.50, and ignore the mass of the finger. FIGURE P12.56arrow_forward
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