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A single plate clutch using both contact planes is used to deliver a torque of 90 Nm. The axial contact pressure on the clutch is 84 kPa, the coefficient of friction is 0.29 and the outer diameter is 1.26 times the inner diameter. Calculate the inner and outer diameters of the clutch required, as well as the required axial force.
A single plate clutch using both contact planes is used to deliver a torque of 90 Nm. The axial contact pressure on the clutch is 84 kPa, the coefficient of friction is 0.29 and the outer diameter is 1.26 times the inner diameter. Calculate the inner and outer diameters of the clutch required, as well as the required axial force.
A lift of mass 1.1 Mg is suspended from a light cable that is wound around a winding drum with a mass of 162 kg, an effective diameter of 500 mm, a radius of gyration of 276 mm and a frictional torque of 120 Nm. The winding drum is driven with a speed ratio of 4 to 1 and an efficiency of 84% by an electric motor of which the rotating parts have a mass of 31 kg, a radius of gyration of 132 mm and a frictional torque of 18 Nm. Determine: 1.1. The torque exerted by the motor to give the lift an upward acceleration of 2.8 m/s2 . (17) 1.2. The maximum constant upward velocity of the lift if the motor develops a maximum power of 16 kW.
A rigid bar, pinned at O, is supported by two identical springs as shown in Fig. Each spring consists of 21
turns of 3⁄4-in-diameter wire having a mean diameter of 6.5 in. Determine the maximum load W that may
be supported if the shearing stress in the springs is limited to 21 ksi.
The bent steel bar shown in figure is 201mm square. Determine the normal stresses at A and B.
A helical spring is provided with a rigid plate at each end. A bolt passes through the spring and the end plates. By turning the nut, the spring is compressed until the coils touch. The height of the unloaded spring is 700 mm, its mean coil diameter is 200 mm, and the diameter of the spring wire is 30 mm. The spring has 20 coils. If the diameter of the bolt is 26 mm and each plate is 26 mm thick. Calculate: a. The elongation of the bolt when the spring is fully compressed b. The stress in the spring wire. (E=200 GPa and G= 80 GPa)
This problem illustrates both the structure of a diatomic molecule and the large disparity between changes in rotational, vibrational, and electronic energy levels. It also illustrates the formation of a band head, the abrupt end of a spectroscopic band. The following data for I2 are available from the NIST website:
(a) Construct an energy-level diagram for the ground electronic state. Consider only the first 10 rotational levels within the first two vibrational levels. Label the ordinate in cm−1 and indicate the total degeneracy of each individual rotational energy level on the diagram. 242
(b) Determine the energies (in cm−1 ) of the 10 purely rotational transitions for the v = 0 energy level within the ground electronic state and plot them on a second energy-level diagram. Draw a vertical line representing v = 0, J = 10 → 9 on the diagram from part (a).
Background A villager in South Africa has an inhabitant of five hundred people. It is 200 km from the nearest Eskom substation based on line of sight. Presently, the only source of electric power in the village is diesel generator. Due to Covid-19, the company that used to maintain the generator has folded up, consequently, the villagers have no electricity. Aim Design a standalone (off grid) Photovoltaic (PV) system with special reference to the village in South Africa with the following PV panel generation factors: Group Number PV panel generation factor A 8.5 B 8 C 7.8 D 7 E 7.5 G 7.2 F 8.4 G 7.5 Use any medium of communication available to group yourselves into a maximum of eight (8) members per group and name your groups as per the group numbers in the table above respectively. A typical platform to be used for communication could be myUnisa (discussion forum), Whatsup, Zoom, MS Teams etc. Choose PV panel generation factor based on the group number.
#339914 on Dec 2023