Number 16 2021temperature of a 50 gallon (U.S.) reservoirto 1 the new [r/min]of to 180°F, tbHow many Btus are to raise theIf the in 22 is reduce99FUNDAMENTALS OF MECHANICS AND HEAT12A motor drives a load at cw speed of 1000r/min. The motor develops a cw torque of12 N•m, and the load exerts a ccw torque of(Note: The torque exerted byremains the same.)The electric motor in a trolley bua power output of 80 hp at 1200 rbus moves up a hill at a speed of 315 N.m.a. Will the speed increase or decrease?b. If this situation persists for some time, inwhat direction will the shaft eventuallywill it takeelectric heahour. Assuming that theA large incperrotate?25gear|a. The torque developed by the monb. The force opposing the motion ofmetallic b'13Referring to Fig. 12, if Ty = 40 N-m, whatis the power delivered by the motor?using an atemperaturun hotte%3D[N] snqCalculate the heat [MJ] required to14Referring to Fig. 13, if Ty = 40 N-m and= 50 r/min, calculate the power deliveredby the motor.26An electsn¡ =an area cperatureture is 2is giverpoint oto 100°C.15Referring to Fig. 14, if Ty = 40 N-m and50 r/min, calculate theby the motor.Repeat Problem 20 for 100 kg ofpower receivedaluminum.22The motor in Fig. 23 drives a hoist,Intermediate levelDuring a prony brake test on a motor (seeFig. 4), the following scale and speed read-ings were noted:mass m of 800 kg at a uniform rate of5 m/s. The winch has a radius of 20 cmCalculate the torque [N-m] and speed[r/min] of the motor.AnswersNote: Therounded oare prececol.W P, = 5 lbfP = 28 lbf%3D%3D1.392 N 2.14.5 hp 7a8.415.7 J13. zero 1-n = 1160 r/minIf the diameter of the pulley is 12 inches,calculate the power output of the motor inkilowatts and in horsepower.17A motor drives a flywheel having a moment ofinertia of 5 kg•m?. The speed increases from1600r/min to 1800 r/min in 8 s. Calculatea. the torque developed by the motor [N•m]b. the energy in the flywheel at1800 r/min [kJ]c. the motor power [W] at 1600 r/mind. the power input [W] to the flywheel at1750 r/minWMotorFigure 23Electric hoist, Problem 22.23to 1 m/s, calculate the new speed [r/mintorque [ft•lbf] of the motor.18 A dc motor coupled to a large grinder devel-ops 120 hp at a constant speed of 700 r/min.The moment of inertia of the revolving partsis 2500 lb-ft².a. Calculate the torque [N m] developed bythe motor.Industrial applicationHow manyBtus are required to raise the24temperature of a 50 gallon (U.S.) reservob. Calculate the motor torque [N•m] neededaneed will increase țo 750of water from 55°F to 180°F, assumingingulated, How long

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Accepted Answer

Using 
P =2πNT/60