題組內容

2. An elevator A of total mass 800 kg and a counterweight B of mass 300 kg are shown in Figure 2. The elevator is driven by an electric motor. Determine the efficiency of the motor in the following cases. Assume that the pulleys are massless and neglect axle friction.
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(2) The elevator is moving upwards with a velocity of 1.5 m/s and an acceleration of 1.2 m/s . The power delivered to the motor is 15.1 kW.(10%)