Long term exposure to waves can cause sunburns and skin cancer

Which statement about covalent bonds is true

An object moves from the position +34m to the position -15m in 15 seconds. what is it's total displacement? what is it's average velocity?

30 points - when can a theory be modified if a new type of technology allows for new observations that raise new questions? a. immediately, while the questions about the theory are being asked b. after new hypotheses related to the theory are tested in experiments c. only after the new observations disprove all parts of the theory d. while scientists begin to think about how the theory could improve