During which time interval is the velocity of the object constant?

unable to answer the rest since your question is incomplete

two charges are fixed in place on the x-axis as shown. the charge at x = 0 is negative and has magnitude q = 2 μcoulombs (1 μcoulomb = 10-6 coulombs). the charge at x = d, (d = +12 cm), is positive and has magnitude q = 4 μcoulombs. find a point x = xo along the x-axis at which the electric field is zero.

at positions a, g kinetic energy is maximum.

at position d, potential energy is maximum.

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.