2kg ball rolling off a 40 meter building

Two identical 82 mg dust particles very far apart (pee 0) are moving directly toward each other at a speed of 3698 m/s. the charge on each is-719 ? c. determine how close they will get to each other. let k = 9x109 n-m2/c2 & ignore gravity.

What is the acceleration of a spaceship that is initially at rest and then speeds up to 220 m/s in 20 seconds

Are good conductors of heat also good conductors of electricity? explain your answer.