A 1200 kg car traveling 3.0 m/s to the north runs into a telephone pole. The telephone pole completely stops the car. Which of the following is true?
A. Momentum is not conserved because outside forces act on the
system
B. The momentum of the telephone pole after the collision is 3600
kg•m/s to the north.
C. The momentum of the telephone pole after the collision is 3600
kg m/s to the south.
D. The total momentum before the collision equals the total
momentum after the collision.

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.