Abrick is lying on a table in a state of static equilibrium. if the mass of the brick is 7.52 kilograms, what is the normal force exerted by the table on the brick?

a. −73.7 newtons
b. 73.7 newtons
c. 80.7 newtons
d. 7.52 newtons
e. 8.07 newtons

i believe the answer is either a. or b.—i'm just not sure if it should be expressed as a negative or not because the force is acting in the opposite direction.

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.