What are some things that are true about an atom with a mass of 15 amu​

Imagine you had to physically add electrons, one at a time, to a previously neutral conductor. you add one electron very easily, but the second electron requires more work. in your initial post to the discussion, explain why this is. also, what happens to the work needed to add the third, fourth, fifth, and subsequent electrons

Which type of wave can travel without a medium

The coefficient of friction is a number that represents the resistance to sliding between two in contact with one another.