1.Two materials that can be scratched by an iron mail are ___, ___ 2.What is the substance that can be scratched by an iron nail but not a penny?
Please answer

Lightning is an example of what phenomenon? a release of a large amount of energy an absorption of a large amount of energy a natural electric circuit a natural electric current

What kind of simple machine is a catapult?

Sawyer is studying diffraction. he draws a diagram of a plane wave to show how light waves travel. which best describes sawyer’s error? the wave fronts should be perpendicular to the direction in which the waves move. the arrow showing the direction of movement of the waves should be pointing to the left. the arrow showing the direction of movement of the waves should be pointing downward. the wave fronts should be both parallel and perpendicular to the direction in which the waves move.