An object moves, along a line, from point A to B to C and then back to B again as shown in the figure below in half an hour.
a) find the average speed of the moving object in km/hr.
b) find the magnitude of the average velocity of the object in km/hr

Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.