Look at the two question marks between zinc (Zn) and arsenic (As). At the time, no elements were known
with atomic weights between 65.2 and 75. But Mendeleev predicted that two elements must exist with
atomic weights in this range. What led Mendeleev to predict that two undiscovered elements existed in
that range?

Two manned satellites approaching one another at a relative speed of 0.550 m/s intend to dock. the first has a mass of 2.50 ✕ 103 kg, and the second a mass of 7.50 ✕ 103 kg. assume that the positive direction is directed from the second satellite towards the first satellite. (a) calculate the final velocity after docking, in the frame of reference in which the first satellite was originally at rest.(b) what is the loss of kinetic energy in this inelastic collision? (c) repeat both parts, in the frame of reference in which the second satellite was originally at rest. final velocity(d) loss of kinetic energy = ?