Concept explainers
The Bunchberry
The bunchberry flower has the fastest-moving parts ever seen in a plant. Initially, the stamens are held by the petals in a bent position, storing energy like a coiled spring. As the petals release, the tips of the stamens fly up and quickly release a burst of pollen.
Figure P7. 72 shows the details of the motion. The tips of the stamens act like a catapult, flipping through a 60° angle; the times on the earlier photos show that this happens in just 0.30 ms. We can model a stamen tip as a 1.0-mm-Jong, 10 μg rigid rod with a 10 μg anther sac at one end and a pivot point at the opposite end. Though an oversimplification, we will model the motion by assuming the
Figure P7.72
72. What is the angular acceleration of the anther sac during the motion?
A. 3.5 × 103 rad/s2
B. 7.0 × 103 rad/s2
C. 1.2 × 107 rad/s2
D. 2.3 × 107 rad/s2
Want to see the full answer?
Check out a sample textbook solutionChapter 7 Solutions
College Physics: A Strategic Approach (3rd Edition)
Additional Science Textbook Solutions
Campbell Biology in Focus (2nd Edition)
Biology: Life on Earth (11th Edition)
Human Anatomy & Physiology (2nd Edition)
Chemistry: Structure and Properties (2nd Edition)
Cosmic Perspective Fundamentals
Concepts of Genetics (12th Edition)
- A Ferris wheel on a California pier is 27 m high and rotates once every 32 seconds. When the wheel starts turning, you are at the very top.a. What is your angular position 75 seconds after the wheel starts turning, measured counterclockwise from the top?Express your answer as an angle between 0° and 360°.b. What is your speed ν?arrow_forwardThe following figure shows the cross section of a cylinder of radius 3.6 m rotating about its axis at :3.7 rad/s. The speed of the point P is P. m/s 41.85 .a O m/s 13.32 .b O Can not be determined .c O rad/s 13.32 .dO rad/s 41.85 .e Oarrow_forwardA. A wheel accelerates for 20 s from rest to 30,000 revolutions per minute. What is the the average angular acceleration in rad/s2 B. A wheel accelerates for 20 s from rest to 30,000 revolutions per minute.Find the number of revolutions the wheel turned. (the angular acceleration is constant)arrow_forward
- A clever witch is social distancing during trick-or-treating by sticking her pumpkin-shaped bucket full of candy on the end of her broomstick. Her broomstick has a length of L = 1.2 m and she holds it Broomstick ly. The broomstick has a mass of 1.10 kg and the pumpkin has a mass of 2.4 kg. The witch holds her hands a distance of d = 0.80 m apart. L d. What is the force from the hand on the end of the broom? This is the hand on the left in the figure. FL = What is the force from the hand closer to the middle of the broom? This is the hand on the right in the figure. FR = Narrow_forwardTwo horizontal rods are each held up by vertical strings tied to their ends. Rod 1 has length L and mass M; rod 2 has length 24 and mass 2M. Each rod then has one of its supporting strings cut, causing the rod to begin pivoting about the end that is still tied up. Which rod has a larger initial angular acceleration? A. Rod 1 B. Rod 2 C. The initial angular acceleration is the same for both.arrow_forwardFigure OQ10.8 shows a system of four particles joined by light, rigid rods. Assume a = b and M is larger than m. About which of the coordinate axes does the system have (i) the smallest and (ii) the largest moment of inertia? (a) the x axis (b) the y axis (c) the z axis. (d) The moment of inertia has the same small value for two axes. (e) The moment of inertia is the same for all three axes. Figure OQ10.8arrow_forward
- A ball rolls to the left along a horizontal surface, up the slope, and then continues along a horizontal surface (Fig. P12.70). Sketch the angular speed and the magnitude of the angular acceleration of the ball as functions of time. FIGURE P12.70arrow_forwardA rotating objects angular position is given by (t) = (1.54t2 7.65t + 2.75) rad, where t is measured in seconds. Find a. the objects angular speed when t = 3.50 s and b. the magnitude of the angular acceleration when t = 3.50 s.arrow_forwardA long, thin rod of mass m = 5.00 kg and length = 1.20 m rotates around an axis perpendicular to the rod with an angularspeed of 3.00 rad/s. a. What is the angular momentum of therod if the axis passes through the rods midpoint? b. What is theangular momentum of the rod if the axis passes through a pointhalfway between its midpoint and its end?arrow_forward
- A cam of mass M is in the shape of a circular disk of diameter 2R with an off-center circular hole of diameter R is mounted on a uniform cylindrical shaft whose diameter matches that of the hole (Fig. P1 3.78). a. What is the rotational inertia of the cam and shaft around the axis of the shaft? b. What is the rotational kinetic energy of the cam and shaft if the system rotates with angular speed around this axis?arrow_forwardA 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_forwardThe figure shows a golf ball passing through a windmill at a miniature golf course. The windmill has 8 blades and rotates at an angular speed of 2.34 rad/s. The opening between successive blades is equal to the width of a blade. A golf ball of diameter 5.97 x 10-2 m is just passing by one of the rotating blades. What must be the minimum speed of the ball so that it will not be hit by the next blade? Number i Units Golf ballarrow_forward
- University Physics Volume 1PhysicsISBN:9781938168277Author:William Moebs, Samuel J. Ling, Jeff SannyPublisher:OpenStax - Rice UniversityPhysics 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
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning