Ball a, with a mass of 10kg, is moving to the right at 20 m/s. ball b is moving to the left at 20 m/s. upon collision, ball b comes to a standstill, and ball a moves to the left at twice its original speed. what is the mass of ball b? show your work

an ion is a charged atom or molecule. it is charged because the number of electrons do not equal the number of protons in the atom or molecule. an atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.