PHYSICS 135 Chapter Notes - Chapter 7: Kilowatt Hour, Elastic Energy, Vehicle-To-Grid
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6. 6 10 j mgy y+ is upward. (75 kg)(9. 80 m/s )(1350 m 2400 m) (75 kg)(9. 80 m/s )(2400 m 1500 m) 5 gravu increases when the altitude of the object increases. cos. Set up: the lifting force acts in the same direction as the sack(cid:146)s motion, so. Evaluate: the results are independent of the speed. Identify: use the free-body diagram for the bag and newton"s first law to find the force the worker applies. Since the bag starts and ends at rest, (a) for constant speed, the net force is zero, so the required force is the sack(cid:146)s weight, to the sack to find the force. m= f a. This work becomes potential energy. (49. 0 n) (15. 0 m) 735 j. Set up: a sketch showing the initial and final positions of the bag is given in figure 7. 3a. is the horizontal force applied by the worker. The free-body diagram is given in figure 7. 3b.
