The deligne dam on the cayley river is built so that the wall facing the water is shaped like the region above the curve y = 0.3 x 2 y=0.3x2 and below the line y = 120 y=120. (here, distances are measured in meters.) the water level is 30 30 meters below the top of the dam. find the force (in newtons) exerted on the dam by water pressure. (water has a density of 1000 kg m 3 1000kgm3, and the acceleration of gravity is 9.8 m sec 2 9.8msec2 .)

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?