Question 7 of 8 - /15 E Chapter 7: Homework 1 Part 3 Question 8 of 8 - /15 E : Current Attempt in Progress (c) A spring whose stiffness is 890 N/m has a relaxed length of 0.64 m. If the length of the spring changes from 0.54 m to 0.93 m, what is the change in the potential energy of the spring? 160 grams of boiling water (temperature 100 C, heat capacity 4.2 J/gram/K) are poured into an aluminum pan whose mass is 870 grams and initial temperature 25C (the heat capacity of aluminum is 0.9 J/gram/K). Change of potential energy = i Save for Later Part 1 Attempts: 0 of 4 used Submit Answer (a) After a short time, what is the temperature of the water? Thinal = i Save for Later Part 4 Attempts: 0 of 4 used Submit Answer (d) You observe someone pulling a block of mass 48 kg across a low-friction surface. While they pull a distance of 4 m in the direction of motion, the speed of the block changes from 4 m/s to 6 m/s. Calculate the magnitude of the force exerted by the person on the block. Part 2 F = i N (b) What simplifying assumptions did you have to make? Save for Later The thermal energy of the aluminum doesn't change. Attempts: 0 of 4 used O The thermal energy of the water doesn't change. Submit Answer Energy transfer between the system (water plus pan) and the surroundings was negligible during this time. The heat capacities for both water and aluminum hardly change with temperature in this temperature range. Part 5 Save for Later (e) What was the change in internal energy (chemical energy plus thermal energy) of the person pulling the Attempts: 0 of 4 used Submit Answer block? Change in internal energy = i Part 3 Save for Later Attempts: 0 of 4 used Submit Answer (c) Next you place the pan on a hot electric stove. While the stove is heating the pan, you use a beater to stir the water, doing 24730 J of work, and the temperature of the water and pan increases to 85.6 C. How much energy transfer due to a temperature difference was there from the stove into the system consisting of the water plus the pan? SUPPORT Q = i 23 Save for Later SUPPORT Attempts: 0 of 4 used Submit