You’re working for the summer with an ornithologist who knows you’ve studied physics. She asks you for a noninvasive way to measure birds’ masses. You propose using a bird feeder in the shape of a 50-cm-diameter uniform disk of mass 340 g, suspended by a wire with torsional constant 5.00 Nm/rad(see Figure below). Two birds land on opposite sides and the feeder goes into torsional oscillation at 2.6 Hz. Assuming the birds have the same mass, what is it?

A thin rod of mass 0.800 kg and length 0.700 m has a fixed pivot at one end.  The rod is held horizontally and released from rest.  The rod swings downward and back up again like a pendulum.  The rotational inertia of a thin rod rotating about one end is I=13ML2.  Disregard friction and air resistance.(a) Determine the initial angular acceleration of the rod just as it is released.(b) Determine the maximum angular speed of the rod as it swings back and forth.

A uniform thread of linear mass density λ=2. 0 g/m passes through a fixed ideal pulley. At its ends, the thread is stacked into two heaps that do not interfere motion of the thread. A beetle of mass m=80 g tries to manage itself at a constant height on the thread by adjusting its speed relative to the thread

A body oscillates with simple harmonic mo- tion along the x-axis. Its displacement varies with time according to the equation x(t) = A sin(wt+o). If A = 7 m, w = 3.897 rad/s, and = 1.0472 rad, what is the acceleration of the body at t = 3 s? Note: The argument of the sine function is in radians rather than degrees. Answer in units of m/s². Answer in units of m/s².

You have a metal spring of negligible mass that has spring constant k. The spring is supporting an object of mass m which is oscillating up and down with an angular frequency of w. What happens when a large steady current passes through the spring? O The oscillations gradually slow down until they come to a complete stop O The mass continues to oscillate with a reduced oscillation period O The mass continues to oscillate with an increased oscillation period O The mass continues to oscillate with the same oscillation period

An object hanging from a vertical spring oscillates with a period of 0.35 s. Suppose the same object and spring are placed on a horizontal frictionless surface and the object is in a horizontal circle swung (uniform circular motion) with the open end of the spring as the pivot. How many rotations per minute is needed to stretch the spring by 15%?

Chapter 15, Problem 72 Z Your answer is partially correct. Try again. A uniform circular disk whose radius R is 17.0 cm is suspended as a physical pendulum from a point on its rim, (a) What is its period? (b) At what radial distance r< R is there a pivot point that gives the same period? (give answer in cm) (a) Numberx Units (b) Numberx Units cm

This was rejected the first time. Can you please state why this is being rejected?

Help me for part (A) only,To find the torsional constant expression.

= A pendulum consists of a rod of mass 1.80 kg and length L 1.00 m with a solid sphere at one end with mass 0.320 kg and radius 24.0 cm (see the following figure). If the pendulum is released from rest at an angle of 0 = 29.0°, what is the angular velocity at the lowest point? Axis A Part 1 + To solve this problem it will be necessary to first find the moment of inertia of the pendulum. What is its moment of inertia? Part 2 + What is the initial gravitational potential energy of the pendulum? Define the gravitational potential energy to be zero when the pendulum is at its lowest point. Part 3 What is the angular velocity of the pendulum at its lowest point?