Marc attaches a falling 500-kg object with a rope through a pulley to a paddle wheel shaft. he places the system in a well-insulated tank holding 25 kg of water. when the object falls, it causes the paddle wheel to rotate and churn the water. if the object falls a vertical distance of 100 m at constant speed, what is the temperature change of the water? (1 kcal = 4 186 j, the specific heat of water is 4 186 j/kgc, and g = 9.8 m/s2)

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?