Lake Mead, the reservoir above Hoover Dam, has a surface area of approximately 640 km2. The top 1 meter of water in the lake weighs about 6.3 x 1012 N. The dam holds that top layer of water 220 m above the river below, What is the potential energy of the top 1 m of water in Lake Mead. Group of answer choices

140800 j

2156 j

1.38 x 10^15 j

14367.3 j

Cells in the nervous system have a potential difference of 70 mv across the cell membrane separating the interior of the cell from the extracellular fluid. this potential difference is maintained by ion pumps that move charged ions across the membrane. is this an emf? select the correct answer and explanation. 1)no. the ion pumps cannot separate charges; thus, they cannot create a potential difference. 2)yes. the ion pumps cannot separate charges, but they still can create a potential difference. 3)yes. the ion pumps can actively separate charge; thus, they can create a potential difference. 4)no. the ion pumps can separate charges, but they cannot create a potential difference.