At t=0 the current to a dc electric motor is reversed, resulting in an angular displacement of the motor shaft given by 0(t) =(240 rad/s)t-(20.9 rad/s² )t2-(1.60 rad/s³ )t³.

a rotating wheel stores energy.  It rotates 400 rad/s to store 1.00 x 106 J. What is the moment of Intertia in kg x m2 ?

P=V+18+90² 2.Ifr= {Si}mand F = (-10k) N, the moment rx F equals { _N.m. P₁-

A potter's wheel—a thick stone disk with a radius of 0.570m and a mass of 118kg—is freely rotating at 41.0rev/min. The potter can stop the wheel in 5.30s by pressing a wet rag against the rim and exerting a radially inward force of 68.1N. Calculate the effective coefficient of kinetic friction between the wheel and the rag.

The angular displacement of the centrifuge is given by 0 = 4[t+38e-0.029t-38] rad, where t is in seconds and t = 0 is the startup time. If the person loses consciousness at an acceleration level of 7.7g, determine the time t at which this would occur. Verify that the tangential acceleration is negligible as the normal acceleration approaches 7.7g. Answer: ti 28.11 8 sec

Calculate the rotational inertia of a wheel that has a kinetic energy of 33.2 kJ when rotating at 923 rev/min. Number Units Use correct number of significant digits; the tolerance is +/-2%

In the figure, two 5.70 kg blocks are connected by a massless string over a pulley of radius 140 cm and rotational inertia 7.40 x 104 kg-m². The string does not slip on the pulley: it is not known whether there is friction between the table and the sliding block; the pulley's axis is frictionless. When this system is released from rest, the pulley turns through 1.20 rad in 126 ms and the acceleration of the blocks is constant. What are (a) the magnitude of the pulley's angular acceleration, (b) the magnitude of either block's acceleration, (c) string tension T, and (d) string tension T;? Assume free-fall acceleration to be equal to 9.81 ms?. (a) Number Units (b) Number Units (c) Number Units (d) Number Units >

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The following equation provides the relationship between the electrical frequency and the rotational speed of a generator; the standard for electrical frequency in Canada is 60 Hz. f = nm * P / 120 Where: f = Electrical frequency (Hz) nm = Rotor speed in revolutions per minute (rpm) P = Number of poles If a generator has 6 poles, what would be the rotor speed, nm, for a generator located in Canada? Select one:a. 1800 rpmb. 2400 rpmc. 1200 rpmd. 600 rpm

In a satellite model for a science project, given the masses of the three satellites mA=1.4 kg, mp=2.8 kg, and mc =4.6 kg that are connected with massless rods, joined at the point the rotation axis is passing through. The satellites have the distances RA=1 m, RB rad = 0.9 m, and Rc =1.5 m, from the rotation axis. The system rotates with an angular speed w = 2.3 mA RA RB Rc MB 1. Calculate the moment of inertia /; for this model: /; = kg m² 2. Calculate the magnitude of the angular momentum L; = m2 kg 3. Calculate the rotational kinetic energy K;= 4. As the system is rotating counter-clockwise the direction of the vector is The mass mc was not properly glued and breaks away during the rotation. 1. Calculate the moment of inertia If for this model now. If= kg m2 2. Using the conservation of angular momentum, calculate the angular speed wf after the mass mc has broken away during rad the rotation. Wf= 3. Calculate the rotational kinetic energy in this situation: K=