An object moving at 38m/s takes 4s to come to a stop. what is the object’s acceleration?

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.

The energy released by a nuclear fusion reaction is produced when

This is the number of complete movements of a wave per second.