Which answer accurately describes the difference between speed and velocity? question 8 options:
a. speed can be constant or it can change. velocity is always constant.
b. speed requires direction. direction doesn't matter when calculating velocity.
c. speed is the distance per unit of time. velocity is the displacement per unit of time.
d. speed is the same as average velocity. velocity is used to calculate 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.