Momentum is conserved in all collisions. if the initial motion of two trucks are known before a collision, the conservation of momentum can be used as long as what other information is known?
a) the masses of each car must be known.
b) the final motions of each car must be known.
c) the direction each car moves after collision must be known.
d) the distance each car traveled after the collision must be known.

Large electric fields in cell membranes cause ions to move through the cell wall. the field strength in a typical membrane is 1.0 x 10 7 n/c. what is the magnitude of the force on a calcium ion with charge +e? what is its acceleration? is it possible for a particle with the same charge as as calcium to have a different acceleration if placed at this location? what would change the acceleration: mass of the particle? diameter of the particle?