Question 21

(HW T: Kinematics and Dynamics of Rotation Item 21 A bicycle wheel is mounted on a f'oted. frictionless axle. 4. with a light string wound around its rim. The wheel has moment of inertia I = Irma-2. where m is its mass. 7' is its radius. and F: is a dimensionless constant between zero and one. The wheel is rotating counterclockwise with angular speed mg. when at time t = [i someone starts pulling the string with a force of magnitude F. Assume that the string does not slip on the wheel. 1-- Figure 1 DH Review | Constants Part A Suppose that after a certain time to the string has been pulled through a distance L. What is the final rotational speed wfinal of the wheel? Express your answer in terms of L, F, I, and wo. > View Available Hint(s) AEd ? Wfinal = SubmitPart B What is the instantaneous power P delivered to the wheel via the force F at time t = 0? Express the power in terms of some or all of the variables given in the problem introduction. > View Available Hint(s) VO AEd P = Submit(HW T: Kinematics and Dynamics Of Rotation Item 25 Ateenager is standing at the rim ofa large horizontal un'rfonn wooden disk that can rotate ireer about a vertical axis at its center. The mass ofthe disk [in kg) is M and its radius [in m) is R. The mass of the teenager [in kg] is m. The disk and teenager are initially at rest. The teenager then throws a large rock that has a mass [in kg] of mg. As it leaves the thrower's hands. the rock is traveling horizontally with speed 1: [in mfg] relative to the earth in a direction tangent to the rim of the disk. The teenager remains at rest relative to the disk and so rotates with it after throwing the rock. I Review | Constants V PartA In terms of M: R: m. mm and tr, what is the angular speed ofthe disk? Treat the teenager as a point mass. Express your answer in terms of the variables M. R, m, mmk, and 1:. ~ o w: R_equestAnswer Provide Feedback Next >