Lidia plans an experimental investigation to see how the thickness of a lens affects the point where a beam of light is focused. she plans to shine light through a lens and measure the distance to a screen that is placed where the beam focuses. what are the controls in lidia’s investigation?

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?

1kg of water needs to recieve 4200j of energy to go from 90 degrees to 91 degrees. what is the specific heat capacity of water? what are the units?

Notice how they put future which of the clouds shown would indicate a possible future rain storm? a) b) c) d)