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Fig. P16.75
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- A 255-lbf block is suspended from an inextensible cable which is wrapped around a drum of 1.75-ft radius rigidly attached to a flywheel. The drum and flywheel have a combined centroidal moment of inertia 12 lb . ft . s 2 . At the instant shown, the velocity of the block is unknown directed downward. Knowing that the bearing at A is poorly lubricated and that the bearing friction is equivalent to a couple M of magnitude 65 lb .ft, determine the velocity of the block before it has moved 3.5 ft downward if at S2 speed is 13.5ft/sarrow_forwardLocate mass A at 35 mm from support X. 4.4. Locate mass B at 96.5 mm from support X. 4.5. Locate mass C at 122.7 mm from support X. 4.6. Position mass A at zero degrees and D at 90o from A. 4.7. Rotate the shaft by hand and release it. As the shaft is released masses should remain in any angular position. 4.8. Change the angular position of masses B and D till the shaft is statically balanced. 4.9. Rotate the shaft with the motor at high speed and notice the reaction of the system. High vibration and noise indicate that the system is out of balance. 4.10. Change the position of the mass D till the system is dynamically balanced.arrow_forwardThe flywheel of a small punch rotates at 300 rpm. It is known that 1800 ft.1b of work must be done each time a hole is punched. It is desired that the speed of the flywheel after one punching be not less than 90 percent of the original speed of 300 rpm. (a ) Determine the required moment of inertia of the flywheel. (b) If a constant 25-1b.ft couple is applied to the shaft of the flywheel, determine the number of revolutions that must occur between each punching, knowing that the initial velocity is to be 300 rpm at the start of each punching.arrow_forward
- Q2. Two uniform disks of the same material are attached to a shaft as shown. Disk A has a weight of 10 lb and a radius r = 6 in. Disk B is twice as thick as disk A. Knowing that a couple M of magnitude 22 lb. ft is applied to disk A when the system is at rest, determine the radius nr of disk B if the angular velocity of the system is to be 480 rpm after 5 revolutions. A M b B 2barrow_forwardA shaft with 3 meters span between two bearings carries two masses of 10 kg and 20 kg acting at the extremities of the arms 0.45 m and 0.6 m long respectively. The planes in which these masses rotate are 1.2 m and 2.4 m respectively from the left end bearing supporting the shaft. The angle between the arms is 60°. The speed of rotation of the shaft is 200 r.p.m. If the masses are balanced by two counter-masses rotating with the shaft acting at radii of 0.3 m and placed at 0.3 m from each bearing centers, estimate the magnitude of the two balance masses and their orientation with respect to the X-axis, i.e. mass of 10 kg Note: It must be solved using the graphic method, not the equations method.arrow_forward3. The 10-in.-radius brake drum is attached to A a larger flywheel which is not shown. The total mass moment of inertia of the flywheel and drum is 16 lb · ft · s² and the coefficient of kinetic 6 in. friction between the drum and the brake shoe is В 0.40. Knowing that the initial angular velocity is 240 rpm clockwise, determine the force which must be exerted by the hydraulic cylinder if the system is to stop in 75 revolutions. 12 in. D Use work-energy equation. 10 in. +6 in.-arrow_forward
- A shaft with 3 meters span between two bearings carries two masses of 120 g and 100 g acting at the extremities of the arms 40 mm and 50 mm long respectively. The planes in which these masses rotate are 1.5 m and 2.5 m respectively from the left end bearing supporting the shaft. The angle between the arms is 120°. The speed of rotation of the shaft is 200 r.p.m. If the masses are balanced by two counter-masses rotating with the shaft acting at radii of 0.3 m and placed at 0.5 m from each bearing centers, estimate the magnitude of the two balance masses and their orientation with respect to the X-axis, i.e. mass of 120 g.arrow_forwardProblem No. 6 A rotating shaft is to carry four discs A, B, C and D whose masses are 15 kg, 25 kg, 20 kg and 18 kg respectively; they are to be spaced at intervals of 30 cm, 37.5 cm and 22.5 cm along the shaft. The centers of mass of A, B and C are at 3.6 cm, 1.2 cm and 1.8 cm respectively from their axis of rotation. a) The three discs A, B and C are first attached to the shaft, at the spacings specified above, with their centers of mass in positions which give static balance. Find the relative angular positions of their centers of mass. b) The disc D is then attached to the shaft in such a position as to nullify the out of balance couple, when the reference plane passes through A. Find the eccentricity of the centre of mass of D and its angular position relative to that of A.arrow_forwardEXERCISE 5.16 The origin of the xyz coordinate system coincides with the centroid of the upper face of the box. The mass of the box is 10 kg. Determine Ixx, Iyy, and Ixy as functions of 0. Rectangular parallelepiped b/2 as b/2 G az F02 fc2 m = pabc, Lxx = 1/2m (b²+ c²), Iyy = 1/2m(a² + c²), z = - 1/2m (a² + b²). 20 mm 80 mm- 40 mm ·xarrow_forward
- Question No.15: A shaft carries four masses A, B, C and D placed in parallel planes perpendicular to the shaft axis and in this order along the shaft. The masses of B and C are 353 N and 245 N respectively and both are assumed to be concentrated at a radius of 15 cm, while the masses in planes A and D are both at a radius of 20 cm. The angle between the radii of B and C is 100° and that between B and A is 190°, both angles being measured in the same sense. The planes containing A and B are 25 cm apart and those containing B and C are 50 cm apart. If the shaft is to be in complete dynamic balance, determine i) Masses of A and D ii) distance between the planes containing C and D iii) angular position of the mass D.arrow_forwardGreek engineers had the unenviable task of moving large columns from the quarries to the city. One engineer, Chersiphron, tried several different techniques to do this. One method was to cut pivot holes into the ends of the stone and then use oxen to pull the column. The 4-ft diameter column weighs 12,000 lbs, and the team of oxen generates a constant pull force of 1500 lbs on the center of the cylinder G. Knowing that the column starts from rest and rolls without slipping, determine (a) the velocity of its center G after it has moved 5 ft, (b) the minimum static coefficient of friction that will keep it from slipping.arrow_forward2. Show that the gravitational self-energy (energy of assembly piecewise from infinity) 3GM? of a uniform sphere of mass M and radius R is U = - 5Rarrow_forward
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