What two types of matter are closest in density? how do you know?

The diagram shows a person using a piece of gym equipment to lift weight which best describe the body in terms of simple machine

How many neutrons does plutonium -196 with an atomic number of 78.

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?