Physics for Scientists and Engineers: Foundations and Connections
1st Edition
ISBN: 9781133939146
Author: Katz, Debora M.
Publisher: Cengage Learning
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Chapter 12, Problem 40PQ
To determine
The reason why a person with weak hands prefer to have a door handle such as the one shown in figure P12.40 instead of a round doorknob.
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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 10 000-N shark is supported by a rope attached to a 4.00-m rod that can pivot at the base. (a) Calculate the tension in the cable between the rod and the wall, assuming the cable is holding the system in the position shown in Figure P12.33. Find (b) the horizontal force and (c) the vertical force exerted on the base of the rod. Ignore the weight of the rod. Figure P12.33arrow_forwardThree forces are exerted on the disk shown in Figure P12.71,and their magnitudes are F3 = 2F2 = 2F1. The disks outer rimhas radius R, and the inner rim has radius R/2. As shown in thefigure, F1 and F3 are tangent to the outer rim of the disk, and F2 is tangent to the inner rim. F3 is parallel to the x axis, F2 is parallel to the y axis, and F1 makes a 45 angle with the negative x axis. Find expressions for the magnitude of each torque exertedaround the center of the disk in terms of R and F1. FIGURE P12.71 Problems 71-75arrow_forwardThe fishing pole in Figure P8.3 makes an angle of 20.0 with the horizontal. What is the magnitude of the torque exerted by the fish about an axis perpendicular to the page and passing through the anglers hand if the fish pulls on the fishing line with a force F=1.00102N at an angle 37.0 below the horizontal? The force is applied at a point 2.00 m from the anglers hands. Figure P8.3arrow_forward
- When a circus performer performing on the rings executes the iron cross, he maintains the position at rest shown in Figure P12.37a. In this maneuver, the gymnasts feet (not shown) are off the floor. The primary muscles involved in supporting this position are the latissimus dorsi (lats) and the pectoralis major (pecs). One of the rings exerts an upward force Fk on a hand as show n in Figure P12.37b. The force Fs, is exerted by the shoulder joint on the arm. The latissimus dorsi and pectoralis major muscles exert a total force Fm on the arm. (a) Using the information in the figure, find the magnitude of the force Fm for an athlete of weight 750 N. (b) Suppose a performer in training cannot perform the iron cross but can hold a position similar to the figure in which the arms make a 45 angle with the horizontal rather than being horizontal. Why is this position easier for the performer? Figure P12.37arrow_forwardA 20.0-kg floodlight in a park is supported at the end of a horizontal beam of negligible mass that is hinged to a pole as shown in Figure P12.10. A cable at an angle of = 30.0 with the beam helps support the light. (a) Draw a force diagram for the beam. By computing torques about an axis at the hinge at the left-hand end of the beam, find (b) the tension in the cable, (c) the horizontal component of the force exerted by the pole on the beam, and (d) the vertical component of this force. Now solve the same problem from the force diagram from part (a) by computing torques around the junction between the cable and the beam at the right-hand end of the beam. Find (e) the vertical component of the force exerted by the pole on the beam, (f) the tension in the cable, and (g) the horizontal component of the force exerted by the pole on the beam. (h) Compare the solution to parts (b) through (d) with the solution to parts (c) through (g). Is either solution more accurate? Figure P12.10arrow_forwardA stepladder of negligible weight is constructed as shown in Figure P12.40, with AC = BC = . A painter of mass m stands on the ladder a distance d from the bottom. Assuming the floor is frictionless, find (a) the tension in the horizontal bar DE connecting the two halves of the ladder, (b) the normal forces at A and B, and (c) the components of the reaction force at the single hinge C that the left half of the ladder exerts on the right half. Suggestion: Treat the ladder as a single object, but also treat each half of the ladder separately. Figure P12.40 Problems 40 and 41.arrow_forward
- The fishing pole in Figure P8.3 makes an angle of 20.0 with the horizontal. What is the magnitude of the torque exerted by the fish about an axis perpendicular to the page and passing through the anglers hand if the fish pulls on the fishing line with a force F=1.00102N at an angle 37.0 below the horizontal? The force is applied at a point 2.00 m from the anglers hands. Figure P8.3arrow_forwardThe fishing pole in Figure P10.28 makes an angle of 20.0 with the horizontal. What is the torque exerted by the fish about an axis perpendicular to the page and passing through the anglers hand if the fish pulls on the fishing line with a force F = 100 N at an angle 37.0 below the horizontal? The force is applied at a point 2.00 in from the anglers hands.arrow_forwardThe fishing pole in Figure P10.22 makes an angle of 20.0 with the horizontal. What is the torque exerted by the fish about an axis perpendicular to the page and passing through the anglers hand if the fish pulls on the fishing line with a force F=100N at an angle 37.0 below the horizontal? The force is applied at a point 2.00 m from the anglers hands. Figure P10.22arrow_forward
- A 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 uniform beam of length L and mass m shown in Figure P12.8 is inclined at an angle to the horizontal. Its upper end is connected to a wall by a rope, and its lower end rests on a rough, horizontal surface. The coefficient of static friction between the beam and surface is s. Assume the angle is such that the static friction force is at its maximum value. (a) Draw a force diagram for the beam. (b) Using the condition of rotational equilibrium, find an expression for the tension T in the rope in terms of m, g, and . (c) Using the condition of translational equilibrium, find a second expression for T in terms of s, m, and g. (d) Using the results from parts (a) through (c), obtain an expression for s involving only the angle . (e) What happens if the ladder is lifted upward and its base is placed back on the ground slightly to the left of its position in Figure P12.8? Explain. Figure P12.8arrow_forwardYou are attending a county fair with your friend from your physics class. While walking around the fairgrounds, you discover a new game of skill. A thin rod of mass M = 0.500 kg and length = 2.00 m hangs from a friction-free pivot at its upper end as shown in Figure P11.43. The front surface of the rod is covered with Velcro. You are to throw a Velcro-covered ball of mass m = 1.0 kg at the rod in an attempt to make it swing backward and rotate all the way across the top. The ball must stick to the rod at all times after striking it. If you cause the rod to rotate over the top position, you win a stuffed animal. Your friend volunteers to try his luck. He feels that the most torque would be applied to the rod by striking it at its lowest end. While he prepares to aim at the lowest point on the rod, you calculate how fast he must throw the ball to win the stuffed animal with this technique. Figure P11.43arrow_forward
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