Problem 3.7-2A motor drives a shaft at 12 Hz and delivers 20 kW ofpower (see figure). (a)If the shaft has a diameter of 30 mm, what is the maximum shearstress maxin the shaft? (b)If the maximum allowable shear stress is 40 MPa, what is theminimum permissible diameter dminof the shaft?Solution 3.7-2Motor-driven shaftSECTION 3.7Transmission of Power217d12 Hz20 kWf12 HzP20 kW20,000 N m/sTORQUEP2f TPwattsfHzs1TNewton meters(a) MAXIMUM SHEAR STRESSmaxd30 mmTP2f20,000W2(12Hz)265.3N .m(b) MINIMUM DIAMETERdminallow40 MPadmin0.0323m32.3mm33.78106m3d316Ttallow16(265.3N .m)(40MPa)50.0MPatmax16Td316(265.3N .m)(0.030m)3Problem 3.7-3The propeller shaft of a large ship has outside diameter 18 in. and inside diameter 12 in., as shown in the figure. The shaft is rated for a maximum shear stress of 4500 psi. (a)If the shaft is turning at 100 rpm, what is the maximumhorsepower that can be transmitted without exceeding the
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