17.43 The rotor of an electric motor has a weight of 70 lb and a radiusof gyration of 10 in. It is observed that 5.3 min is required for the rotor tocoast to rest from an angular velocity of 3600 rpm. Determine the averagemagnitude of the couple due to kinetic friction in the bearings of the rotor.

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Answered: 17.43 The rotor of an electric motor…

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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Dynamic Problem, reply as soon as posible. The double pulley system weighs 30 lbs. and has a 6.5-inch center radius of gyration. Cylinders A and B areconnected to the double pulley by cords that wrap around the circles whose radii are shown. Thecoefficient of kinetic friction between block B and the surface is 0.25. If the system is released from rest atposition shown, determine:A) The velocity of cylinder A just before hitting the ground.B) The total distance cylinder B travels before coming to rest.
A 5.32-kg disk A of radius 0.445 m initially rotating counter-clockwise at 436 rev/min is engaged with a 6.72-kg disk B of radius 0.275 m initially rotating clockwise at 528 rev/min, where the moment of inertia of a disk is given as I = ½ mi?. Determine their combined angular speed (in rpm) and direction of rotation after the meshing of the two disks. Remember to show clearly the equations that you use!!'
A machine shaft running at an average speed of 360 r.p.m requires a constant torque of 1.5 kN-m during two revolutions and a constant torque of 400 N-m during next three revolutions and this cycle repeats. Determine the power of the motor required and moment of inertia of a flywheel in order that the total fluctuation of speed shall not exceed 6 percent of mean speed of 320 r.p.m.
A 240-lb block is suspended from an inextensible cable which is wrapped around a drum of 1.25-ft radius rigidly attached to a flywheel. The drum and flywheel have a combined centroidal moment of intertia of 10.5 lb-ft-s^2. At the instant shown, the velocity of the block is 6 ft/s directed downward. The bearing at A as a frictional moment of 60 lb-ft. What is the kinetic energy of the system after the block moved after 4ft? (in ft-lb)
4. In order to determine the mass moment of inertia of a 4-foot diameter flywheel, the flywheel is tested\twice with different deadweight. In the first test a weight of 20 lb is attached by cord and observed to fall 10 ft in 4.6 seconds. In the second test a weight of 40 lb falls 10 ft in 3.1 seconds. Assuming that the torque due to bearing friction is constant, determine mass moment of inertia of the flywheel. Your solution must include W supporting FBDS.
DYNAMICS OF RIGID BODIES
6. The turbine of a ship has a mass of 4000 kg. and a radius of gyration of 480 mm. It rotates at 2400 rev/min. clockwise when looking forward from the stern. In each of the following cases determine, the magnitude and indicate clearly with suitable diagrams. the effect of the gyroscopic couple acting on the ship: (a) If the ship, when travelling at 15 ms¹ turns to starboard in a curve 1000 m radius. (b) If the ship is pitching and the bow is descending with maximum velocity. The pitching motion is simple harmonic, the period being 20 seconds and the total angular movement is 12º. (c) If the ship is rolling and at a certain instant has an angular velocity of 0.02 rad. s-¹ clockwise when looking forward from the stern.
A shaft turning at a uniform speed carries two uniform discs A and B of masses 10kg and 8kg respectively. The centres of the mass of the discs are each 2.5mm from the axis of rotation. The radii to the centres of mass are at right angles. The shaft is carried in bearings C and D between A and B such that AC = 0.3m, AD = 0.9m and AB = 1.2m. It is required to make dynamic loading on the bearings equal and a minimum for any given shaft speed by adding a mass at a radius 25mm in a plane E. Determine: (a) The magnitude of the mass in plane E and its angular position relative to the mass in plane A (b) The distance of the plane E from plane A (c) The dynamic loading on each bearing when the mass in plane E has been attached and the shaft rotates at 200 rev/min. For the bearing loads in the opposite direction determine all the unknown values. For the bearing loads in the same direction, show the diagrams and equations only to use for a possible solution.
A four-wheeled vehicle of total mass 5000 kg has two pairs of wheels of 500 mm radius. Each pair of wheels with axles has mass of 750 kg, the radius of gyration of each wheel being 400 mm. The axles are 2 metres apart and the c.g. of vehicle is mid-way at a height of 1-2 m above the road surface. Find the reactions of the front and rear wheels, if tractive force of 6 kN is acting 50 mm below the centre of gravity of vehicle.
Solve it correctly please.
Parvinbhai

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