this box if you'd like us to grade this scenario. A student uses a microwave oven to warm 240 g of water from 20°C to 85
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this box if you'd like us to grade this scenario. A student uses a microwave oven to warm 240 g of water from 20°C to 85
this box if you'd like us to grade this scenario. A student uses a microwave oven to warm 240 g of water from 20°C to 85°C. The microwave has an output power of 1350 W. Note, water has a specific heat of 4186 J/kg-K and latent heat of vaporization of 2.26 x 10 J/kg. Multiple Choice Questions (3 points each): Score for this scenario /12 3) Modeling the air inside the microwave as an ideal gas with initial pressure 84.000 Pa, what is the final pressure after it is warmed? Assume that the air inside the microwave oven has the same initial and final temperatures as the water and that the number of air molecules and the volume of air is constant. a) 11.000 Pa c) 69.730 Pa b) 21.000 Pa d) 102.630 Pa e) 110.140 Pa f) 357.000 Pa 4) Assuming 50% of the microwave's power goes into heating the water, how much time does it take for the microwave to warm this water? e) 125 s a) 38 b) 45 s c) 67 s d) 895 f) 16 hours Short Answer Question (6 points): Microwaves-like all electromagnetic waves-travel at the speed of light. In a microwave oven, the waves reflect off of the metal sides of the interior and set up standing waves inside the oven with nodes at each end. For this problem, assume that these standing waves are aligned along the 45 cm interior width of the microwave, and that there are 3 hot spots inside which correspond to the antinodes of this standing waves. • Sketch this standing wave and identify the harmonic (mode number). • What are the frequency and wavelength of this harmonic?
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