Atennis ball is hit into the air with a racket. when is the ball’s kinetic energy the greatest? ignore air resistance. a. when it leaves the racket b. just before it reaches the ground c. when it reaches its maximum height d. when its kinetic energy and potential energy are equal e. just before it starts falling downward

Suppose that a comet that was seen in 563 a.d. by chinese astronomers was spotted again in year 1951. assume the time between observations is the period of the comet and take its eccentricity as 0.986. what are (a) the semimajor axis of the comet's orbit and (b) its greatest distance from the sun?

Along the line connecting the two charges, at what distance from the charge q1 is the total electric field from the two charges zero? express your answer in terms of some or all of the variables s, q1, q2 and k =14ï€ïµ0. if your answer is difficult to enter, consider simplifying it, as it can be made relatively simple with some work.

What is a subatomic particle with a negative charge and very little mass?