Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
4th Edition
ISBN: 9780134110684
Author: Randall D. Knight (Professor Emeritus)
Publisher: PEARSON
expand_more
expand_more
format_list_bulleted
Concept explainers
Textbook Question
Chapter 12, Problem 85EAP
- sThe bunchberry flower has the fastest-moving parts ever observed in a plant. Initially, the stamens are held by the petals in a bent position, storing elastic energy like a coiled spring. When the petals release, the tips of the stamen act like medieval catapults, flipping through a angle in just 0.30 ms to launch pollen from anther sacs at their ends. The human eye just sees a burst of pollen; only high-speed photography reveals the details. As FIGURE CP12.85 shows, we can model the stamen tip as a 10-mm-long, 10 µg rigid rod with a anther sac at the end. Although oversimplifying, we’ll assume a constant
angular acceleration . - How large is the “straightening torque”?
- What is the speed of the anther sac as it releases its pollen?
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solutionStudents have asked these similar questions
Here in Columbus, we're living through a heat wave with an expected heat index of
110 degrees today.
At home, you turn on a fan to cool off, and the fan blades speed up (the fan was off
before you touched it). If the fan blades reach their top speed in exactly 6.5 seconds,
and the acceleration of the fan blades is 2.7 rad/s², what is the top speed in rpm?
Your Answer:
units
Answer
The Bunchberry flower has the fastest moving parts ever observed in a plant. Initially, the
stamens are held by the petals in a bent position, storing elastic energy like a coiled spring. When
the petals release, the tips of the stamen act like medieval catapults, flipping through a 60° angle
in just 0.30 ms.to launch pollen from anther sacs at their ends. The human eye just sees a burst
of pollen; only high speed photography reveals the details. We can model the stamen tip as a
1.0 mm long, 10µg rigid rod with a 10µg anther sac
at the end. Although oversimplifying, we'll assume a
Pollen
Pollen
Anther sac
constant angular acceleration.
A. How large is the "straightening torque"? (you
may assume the torques created by the gravity
1.0 mm
Stamen
force
are
minimal
compared
to
the
straightening torque, and can be ignored.
B. What is the speed of the anther sac as it releases its pollen?
Initial configuration
Final configuration
A ceiling fan with 89-cm-diameter blades is turning at 60 rpm . Suppose the fan coasts to a stop 25 s after being turned off.
What is the speed of the tip of a blade 10 s after the fan is turned off?
Through how many revolutions does the fan turn while stopping?
Chapter 12 Solutions
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
Ch. 12 - Prob. 1CQCh. 12 - If the angular velocity w is held constant, by...Ch. 12 - FIGURE Q12.3 shows three rotating disks, all of...Ch. 12 - 4. Must an object be rotating to have a moment of...Ch. 12 - 5. The moment of inertia of a uniform rod about an...Ch. 12 - 6. You have two solid steel spheres. Sphere 2 has...Ch. 12 - The professor hands you two spheres. They have the...Ch. 12 - Six forces are applied to the door in FIGURE...Ch. 12 - Prob. 9CQCh. 12 - Rank in order, from largest to smallest, the...
Ch. 12 - The solid cylinder and cylindrical shell in FIGURE...Ch. 12 - A diver in the pike position (legs straight, hands...Ch. 12 - Prob. 13CQCh. 12 - A high-speed drill reaches 2000 rpm in 0.50 s. a....Ch. 12 - A skater holds her arms outstretched as she spins...Ch. 12 - A ceiling fan with 80-cm-diameter blades is...Ch. 12 - An 18-cm-long bicycle crank arm, with a pedal at...Ch. 12 - Prob. 5EAPCh. 12 - The three masses shown in FIGURE EX12.6 are...Ch. 12 - The three masses shown in FIGURE EX12.7 are...Ch. 12 - A 100 g ball and a 200 g ball are connected by a...Ch. 12 - A thin, 100 g disk with a diameter of 8.0 cm...Ch. 12 - What is the rotational kinetic energy of the...Ch. 12 - The three200g masses in FIGURE EX12.11 are...Ch. 12 - A drum major twirls a 96-cm-long, 400 g baton...Ch. 12 - The four masses shown in FIGURE EX12.13 are...Ch. 12 - The four masses shown in FIGURE EXI2.13 are...Ch. 12 - The three masses shown in FIGURE EXI2.15 are...Ch. 12 - A 12-cm-diameter CD has a mass of 21 g. What is...Ch. 12 - A 25 kg solid door is 220 cm tall, 91 cm wide....Ch. 12 - Prob. 18EAPCh. 12 - In FIGURE EX12.19, what magnitude force provides...Ch. 12 - The 20-cm-diameter disk in FIGURE EX12.20 can...Ch. 12 - The axle in FIGURE EXI2.21 is half the distance...Ch. 12 - A 4.0-rn-long, 500 kg steel beam extends...Ch. 12 - An athlete at the gym holds a 3.0 kg steel ball in...Ch. 12 - An object’s moment of inertia is 2.0 kg m2. Its...Ch. 12 - An object whose moment of inertia is 4.0 kg m2...Ch. 12 - A 1.0 kg ball and a 2.0 kg ball are connected by a...Ch. 12 - Starting from rest, a 12-cm-diameter compact disk...Ch. 12 - A 4.0 kg, 36-cm-diameter metal disk, initially at...Ch. 12 - The two objects in FIGURE EXI2.29 are balanced on...Ch. 12 - Prob. 30EAPCh. 12 - The 3.0-rn-long, 100 kg rigid beam of FIGURE...Ch. 12 - A 5.0 kg cat and a 2.0 kg bowl of tuna fish are at...Ch. 12 - A car tire is 60cm in diameter. The car is...Ch. 12 - A 500 g, 8.0-cm-diameter can is filled with...Ch. 12 - Prob. 35EAPCh. 12 - A solid sphere of radius R is placed at a height...Ch. 12 - Prob. 37EAPCh. 12 - Evaluate the cross products AB and CD .Ch. 12 - Prob. 39EAPCh. 12 - Force F=10j N is exerted on a particle at 5i+5j m....Ch. 12 - A 1.3 kg ball on the end of a lightweight rod is...Ch. 12 - What are the magnitude and direction of the...Ch. 12 - What is the angular momentum vector of the 2.0 kg,...Ch. 12 - Prob. 44EAPCh. 12 - Prob. 45EAPCh. 12 - A 2.0 kg, 20-cm-diameter turntable rotates at 100...Ch. 12 - Prob. 47EAPCh. 12 - A toy gyroscope has a ring of mass M and radius R...Ch. 12 - Prob. 49EAPCh. 12 - Prob. 50EAPCh. 12 - Determine the moment of inertia about the axis of...Ch. 12 - What is the moment of inertia of a 2.0 kg,...Ch. 12 - Calculate by direct integration the moment of...Ch. 12 - Calculate the moment of inertia of the rectangular...Ch. 12 - a. A disk of mass M and radius R has a hole of...Ch. 12 - Consider a solid cone of radius R, height H, and...Ch. 12 - Prob. 57EAPCh. 12 - A 3.0-m-long ladder, as shown in Figure 12.35....Ch. 12 - In FIGURE P12.59, an 80 kg construction worker...Ch. 12 - Prob. 60EAPCh. 12 - Prob. 61EAPCh. 12 - A 120-cm-wide sign hangs from a 5.0 kg,...Ch. 12 - Prob. 63EAPCh. 12 - Flywheels are large, massive wheels used to store...Ch. 12 - of mass m1and m2are connected by a massless string...Ch. 12 - The 2.0 kg, 30-cm-diameter disk in FIGURE P12.66...Ch. 12 - A 30-cm-diameter, 1.2 kg solid turntable rotates...Ch. 12 - Your engineering team has been assigned the task...Ch. 12 - A hollow sphere is rolling along a horizontal...Ch. 12 - A 750 g disk and a 760 g ring, both 15 cm in...Ch. 12 - A cylinder of radius R, length L. and mass M is...Ch. 12 - The 5.0 kg, 60-cm-diameter disk in FIGURE P12.72...Ch. 12 - A thin, uniform rod of length L and mass M is...Ch. 12 - A long, thin rod of mass M and length L is...Ch. 12 - The marble rolls down the track shown in FIGURE...Ch. 12 - sThe sphere of mass M and radius R in FIGURE...Ch. 12 - A satellite follows the elliptical orbit shown in...Ch. 12 - A 10 g bullet traveling at 400 m/s strikes a 10...Ch. 12 - A 200 g, 40-cm-diameter turntable rotates on...Ch. 12 - Luc, who is 1.80 m tall and weighs 950 N, is...Ch. 12 - A merry-go-round is a common piece of playground...Ch. 12 - A 45 kg figure skater is spinning on the toes of...Ch. 12 - Prob. 83EAPCh. 12 - The earth’s rotation axis, which is tilted 23.5...Ch. 12 - sThe bunchberry flower has the fastest-moving...Ch. 12 - The two blocks in FIGURE CP12.86 are connected by...Ch. 12 - A rod of length L and mass M has a nonuniform mass...Ch. 12 - In FIGURE CP12.88, a 200 g toy car is placed on a...Ch. 12 - Prob. 89EAPCh. 12 - A 75 g, 30-cm-long rod hangs vertically on a...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- A 1.7 kgkg , 20-cmcm-diameter turntable rotates at 140 rpmrpm on frictionless bearings. Two 450 gg blocks fall from above, hit the turntable simultaneously at opposite ends of a diameter, and stick. What is the turntable's angular velocity, in rpmrpm, just after this event? Express your answer to two significant figures and include the appropriate units.arrow_forwardIn (Figure 1), take m₁ = 3.4 kg and m² = 4.2 kg. Figure 5m 8 m/s 4 m m MAD 1.5 m 0 2 m 4 m ma B 30° 1m2 6 m/s X 1 of 1 Part A Determine the z component of the angular momentum Ho of particle A about point O. Express your answer in kilogram-meters squared per second to three significant figures. ΑΣΦΗ Πvec (Ho): = 124.19 Submit Previous Answers Request Answer * Incorrect; Try Again; 2 attempts remaining Part B (Ho): = Determine the z component of the angular momentum Ho of particle B about point O. Suppose that Express your answer in kilogram-meters squared per second to three significant figures. ΕΠΙΑΣΦΠ Submit vec Provide Feedback Previous Answers Request Answer * Incorrect; Try Again; 5 attempts remaining ? kg.m²/s ? kg.m²/sarrow_forwardYou are coasting along on your bike (that has a 0.66 m diameter tire), You notice a twig in your spoke (at 1/2 the radius of the tire) hits the bike frame once per second. What is your speed in m/s?arrow_forward
- A Ferris wheel has a radius of 30 m and its centre is 32 m above the ground. It rotates once every 48 s. Ethan gets on the Feris wheel at the lowest point and then the wheel starts to rotate. The amount of time it takes Ethan to reach 38 m above the ground for the first time, to the nearest tenth of a second, is S. Your answerarrow_forward1. 5r2 and I have two disks. I know that disk A has a mass per unit area o given by o = disk B has o = 3r3. Each disk has radius 10cm. I have a slope at angle 45 degrees to the horizontal that is 2 m long. I time with a stop watch how long it takes the disks to roll down the slope without slipping. (Assuming that the disk's are let go with zero velocity at the top of the slope). a) Calculate the mass of each disk. [4 marks]arrow_forwardIn the figure below, a small disk of radius r = 2.00 cm has been glued to the edge of a larger disk of radius R = 4.10 cm so that the disks lie in the same plane. The disks can be rotated around a perpendicular axis through point O at the center of the larger disk. The disks both have a uniform density (mass per unit volume) of 1.70 x 103 kg/m³ and a uniform thickness of 4.70 mm. What is the rotational inertia of the two-disk assembly about the rotation axis through O? kg · m2 •0arrow_forward
- A sphere, centred on the origin, has radius 31.7 cm, and is spinning at 3 revolutions per second with its axis of rotation along the z-axis. A point is chosen with position vector a = (9, -14, 27) cm on the surface of the sphere. a. Calculate the vector representing the angular velocity of the sphere, w, in rad/s. i+ (1) k rad/s V = b. Calculate the velocity v of point a in units of ms-1 i+ k ms-1 j+ Note the units given in the question. j+arrow_forwardA turntable with a mass of 12 kg and a radius of 1.8 meters spins at a constant angular velocity of 140 rpm. A 3-kg brick with a width of 15 cm and a depth of 30 cm falls onto the turntable, so the brick's center of mass is one meter away from the turntable's center. If there's no friction between the brick and turntable and they eventually spin at the same angular speed, what is their final angular speed, in rev/min or in rad/s? Justify your answer with your rationale and equations used. Moments of Inertia: I disk MR? for rotation about its center of mass parallel to the z-axis. = Iblock 5M (W2 + D² ) for rotation about its center of mass parallel to the z-axis.arrow_forwardA turntable with a mass of 12 kg and a radius of 1.8 meters spins at a constant angular velocity of 140 rpm. A 3-kg brick with a width of 15 cm and a depth of 30 cm falls onto the turntable, so the brick's center of mass is one meter away from the turntable's center. If there's no friction between the brick and turntable and they eventually spin at the same angular speed, what is their final angular speed, in rev/min or in rad/s? Justify your answer with your rationale and equations used. Moments of Inertia: Idisk = MR² for rotation about its center of mass parallel to the z-axis. Iblock = M (W² + D²) for rotation about its center of mass parallel to the z-axis.arrow_forward
- A computer hard disk 8.0 cm in diameter is initially at rest. A small dot is painted on the edge of the disk. The disk accelerates at 700 rad/s^2 for 1/2s, then coasts at a steady angular velocity for another 1/2s. What is the speed of the dot at t= 1.0 s? Through how many revolutions has it turned?arrow_forwardA 17 g audio compact disk has a diameter of 12 cm. The disk spins under a laser that reads encoded data. The first track to be read is 2.3 cm from the axis; as the disk plays, the laser scans tracks farther and farther from the center. The part of the disk directly under the read head moves at a constant 1.2 m/s. a. When a disk is inserted, it takes 2.4 s to spin up from rest. What is the torque of the motor?b. As the disk plays, how does the angular speed change?arrow_forwardWe place a 2.0 m long rod in a vertical position and let it fall. At what speed does the upper end of the rod fly against the horizontal floor, if its lower end doesnt move anywhere? (The solution is 7.7 m / s)arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning
Physics for Scientists and Engineers: Foundations...
Physics
ISBN:9781133939146
Author:Katz, Debora M.
Publisher:Cengage Learning
What is Torque? | Physics | Extraclass.com; Author: Extraclass Official;https://www.youtube.com/watch?v=zXxrAJld9mo;License: Standard YouTube License, CC-BY