2. A 5.20 kilowatt machine does 1.60 x 107 Joules of work. Calculate how long was the machine running. 3. An engine does work at a rate of 8100 watts while exerting a force of 475 N on a vehicle. What is the speed of the vehicle? 4. Claire deTabel starts to wait tables after school for some extra cash. She figures she lifts her tray an average of one hundred times in one night. The tray is on average 4.3 kg and she lifts it approximately 1.0 meter every time. Each time it takes her 1.5 seconds to lift the tray. a. Calculate how much work she does on her tray in one lift. b. Calculate how much work she does lifting her tray in one night. c. Calculate how much power she develops when she lifts her tray each time. d. Calculate how much power she develops for the whole night