Some First Nations people traditionally heated water using stones that had been heated in a fire. These hot stones were placed in water held in leather bags. The stones would heat the water. Using a law of thermodynamics, explain why the stones caused the water to heat up

What is the role of lenses in microscopy?

Where do magnetic lines of force enter earth?

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?