Newton’s second law states that f=m x a (force is mass times acceleration). which example would have the greatest acceleration

Atrain departs from its station at a constant acceleration of 5 m/s. what is the speed of the train at the end of 20s?

The material that keeps its new shape after it is stretched is called?

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.