Question 1 (12%) A portable wireless speaker uses a rechargeable lithium-ion battery to play the music. The battery stores 4000mAh energy and its original voltage is 12V when it's fully charged. When the speaker is operating, the power consumption is 4.8W in constant, but the battery's voltage drops at 0.2V/hour. The speaker stops playing when all the energy consumes. 1) How long can the speaker operate continuously? (3%) 2) Find the total charge in coulombs that flows in the speaker from fully charged to fully discharged when it's operating continuously. (3%) 3) After fully discharged, the battery is charged with a constant current of 2A. During the charging process, the batterys voltage increases at 1V/hour until it caps at 12V. Please determine the total time required to fully charge the battery. (6%)