What subject is physics?

Alandscaper is shopping for landscaping materials. she wants to use materials through which water flows easily. which materials should she choose? check all that apply. clay gravel granite rocks with cracks loosely packed soil

Arigid tank is divided into two equal parts by a partition. one part of the tank contains 3 kg of compressed liquid water at 400 kpa and 60°c while the other part is evacuated. the partition is now removed, and the water expands to fill the entire tank. determine the entropy change of water during this process, if the final pressure in the tank is 40 kpa. use steam tables.

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?