Homework Assignment 5 1. Beginning from rest, an object of mass 20 kg slides down a 5-m-long ramp. The ramp is inclined at an angle of 30º from the horizontal. If air resistance and friction between the object and ramp are negligible, determine the velocity of the object, in m/s, at the bottom of the ramp. 2. A stationary closed system of mass 3 kg undergoes a process in which there is a heat transfer of 150 kJ from the system to the surroundings. The work done on the system is 75 kJ. If the specific internal energy of the system is 450 kJ/kg, what is the final specific internal energy, in kJ/kg? 3. An electric generator coupled to a windmill produces an average electric power output of 15 kW. The power is used to charge a storage battery. Heat transfer from the battery to the surroundings occurs at a constant rate of 1.8 kW. Determine, for 8 hr of operation: a. The total amount of energy stored in the battery, in kJ. b.
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