Electric kettle with the resistance of 20-22 is used to heat:4 kg of water. If the initial temperature of the water is 20°C, how much time-later-will the water boil?
C-water=-4200 J/kg°C. The kettle uses 220 V voltage. I
laatsia Iratilowice
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Total solidification times of three casting geometries are to be compared: a sphere, a cylinder, in which the length-to-diameter ration - 1.0, and a cube. volume = 1000 cm^3 for all three shhapes, and the same casting alloy is used. a) determine the solidification times of each geometry b) based on the results of part (a), which geometric element would make the best riser? c) if the mold constant = 3.5 min/cm^2 in chvorinov's rule, compute the total solidification time for each casting.

Work = force × a. work b. energy c. distance d. momentum

30 points - when can a theory be modified if a new type of technology allows for new observations that raise new questions? a. immediately, while the questions about the theory are being asked b. after new hypotheses related to the theory are tested in experiments c. only after the new observations disprove all parts of the theory d. while scientists begin to think about how the theory could improve