A river is 120km/h wide and the water flows at 2.5km/h. A ferry man who can scull in still water at 3km/h wishes to cross the river in a direction at right angle to it's bank. Find by accurate scale drawing, the direction in which he must steer the boat and the time it takes him to cross. ​

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?