Which type of species would be the prefect option to repopulate an area that is in the primary succession stages? A) secondary species
B) pioneer species
C) extinct species
D) hetero-tropic species

Which is the best for showing percentages of different types of cars sold(gas hybrid , electric , other ) in the united states ?

What is the momentum of a 2 kg object moving at 15 meters per second

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?