HW14 - 14.6 A small immersion heater is rated at 350 W....

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14.6 A small immersion heater is rated at 350 W. Estimate how long it will take to heat a cup of soup (assume this is 250 mL of water) from 20°C to 60°C. The wattage rating is Joules per second. Note that 1 L of water has a mass of 1 kg. () 1o 2 o 1 kg 1 kcal 4186 J 1 s 2.50 10 L 40C 1.2 10 s 2.0 min 1 L kcal 350 J 1 kg 1C ×= × = ⎡⎤ ⎛⎞ ⎜⎟ ⎢⎥ ⎝⎠ ⎣⎦ 14.12 What will be the equilibrium temperature when a 245-g block of copper at 285°C is placed in a 145-g aluminum calorimeter cup containing 825 g of water at 12.0°C? The heat lost by the copper must be equal to the heat gained by the aluminum and the water. ( ) ( ) ( ) ( ) 22 2 Cu Cu Cu eq Al Al eq Al H O H O eq H O o oo o eq eq o o eq 0.145 kg 900J kg C 0.245 kg 390J kg C 285 C 12.0 C 0.825 kg 4186J kg C 19.1 C ii i mc T T mc T T m c T T TT T −= + + = ± ± ± 14.31 A 54.0 kg ice skater moving at s m 4 . 6 glides to a stop. Assuming the ice is at 0°C and that 50% of the heat generated by friction is absorbed by the ice, how much ice melts?
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This note was uploaded on 11/29/2010 for the course PHYSICS PHYS310 taught by Professor Coleman during the Spring '10 term at Rutgers.

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HW14 - 14.6 A small immersion heater is rated at 350 W....

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