Expain why different atoms of the same element always have the same atomic number but can have different mass numbers what are these different atoms called ?

Are formed where bumps from two surfaces come into contact ?

Which of the following is probably the least necessary character trait needed to be a good clinical nurse?

Diego is trying to lift a piano to the second floor of his house. diego uses a pulley system and gives a big lift to the piano.the piano moves upward, then stops, and then it starts to fall to the ground. which list best describes the forces on the piano in the proper order? positive force → balanced force → negative force negative force → balanced force → positive force positive force → unbalanced force → negative force negative force → unbalanced force → positive force